Polycarbonate compositions having enhanced optical properties, methods of making and articles comprising the polycarbonate compositions

ABSTRACT

In some embodiments, a method of making a polycarbonate composition comprises: polymerizing by an interfacial polymerization, reactants comprising a starting material comprising a bisphenol-A to form a bisphenol-A polycarbonate, wherein the bisphenol-A has a purity of greater than or equal to 99.65 wt % and a sulfur content of less than or equal to 2 ppm. The polycarbonate composition has a free hydroxyl content of less than or equal to 150 ppm, and wherein a molded article of the polycarbonate composition has transmission level greater than or equal to 90.0% at 2.5 mm thickness as measured by ASTM D1003-00 and a yellow index (YI) less than or equal to 1.5 as measured by ASTM D1925.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/565,292, now U.S. Pat. No. 9,290,618, filed Aug. 2, 2012, whichclaims the benefit of provisional U.S. Patent Application Ser. No.61/515,365, filed Aug. 5, 2011, both of which are hereby incorporated byreference in their entirety.

BACKGROUND

The present disclosure generally relates to polycarbonate compositions,and more particularly, to polycarbonate compositions having enhancedoptical properties, methods of manufacture, and uses thereof.

Polycarbonate is a high-performance plastic with good impact strength(ductility). Polycarbonates, however, can age under the influence ofheat, light, and time, causing reduced light transmission and colorchanges.

There accordingly remains a need for polycarbonate compositions havingenhanced optical properties, methods of making and articles comprisingthe polycarbonate compositions.

BRIEF DESCRIPTION

Disclosed herein are polycarbonate compositions having enhanced opticalproperties, methods for making the polycarbonate composition, andarticles comprising the polycarbonate compositions.

In one embodiment, a composition comprises a bisphenol-A polycarbonate,wherein a molded article of the composition has transmission levelgreater than or equal to 90.0% at 2.5 mm thickness as measured by ASTMD1003-00 and a yellow index (YI) less than or equal to 1.5 as measuredby ASTM D1925.

In another embodiment, a method of making a polycarbonate compositioncomprises polymerizing, by an interfacial polymerization, reactantscomprising a starting material, the starting material comprising abisphenol-A having a purity of greater than or equal to 99.65 wt % and asulfur content of less than or equal to 2 ppm. The polycarbonatecomposition has a free hydroxyl content of less than or equal to 150ppm, and a molded article of the polycarbonate composition hastransmission level greater than or equal to 90.0% at 2.5 mm thickness asmeasured by ASTM D1003-00 and a yellow index (YI) less than or equal to1.5 as measured by ASTM D1925.

These and other non-limiting characteristics are more particularlydescribed below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph depicting transmission (%) versus wavelength(nanometers (nm)) of polycarbonates.

FIG. 2 is a graph depicting the yellowness and transmission ofpolycarbonate (PC) compared to PMMA (polymethyl methacrylate) andstandard uncoated glass (yellowness index (YI (−)) versus transmission(%)).

FIG. 3 is a schematic illustration of selected BPA impuritiespotentially related to color.

FIG. 4 is a graph depicting changes in YI after 2000 hours, heat agingat 130° C. as a function of spiking level of three different impurities(delta YI(−) versus spiking level (ppm)).

FIG. 5 is a graph depicting the change in YI after 2,000 hours, heataging at 130° C. as a function of the summed level of BPX-1 and opBPA asdetermined analytically (delta YI versus BPX-1+opBPA (ppm).

FIG. 6 is a graph depicting implementation of the described processimprovements combined with an optimized optimized formulation improvedthe polycarbonate (PC) grade beyond comparison performance (delta YI(−)versus time (hours)).

FIG. 7 is an exemplary chemical formula illustrating the formation ofBPA.

FIG. 8 is an example of an exemplary bound catalyst (attached to aninsoluble resin for the reduction of sulfur in BPA.

FIG. 9 is a bar graph comparing the yellowness index (YI) for anexemplary polycarbonate (LEXAN* polycarbonate grade PC175 having a meltvolume rate of 30) with the bulk catalyst (“A”), the attached catalyst(“B”), and with the attached catalyst and a BPA purity of 99.65 wt %.

FIG. 10 is a bar graph comparing the yellowness index (YI) for anexemplary polycarbonate (LEXAN* polycarbonate grade PC105 having a meltvolume rate of 6) with the bulk catalyst (“A”), the attached catalyst(“B”), and with the attached catalyst and a BPA purity of 99.65 wt %(also referred to as “new BPA”).

FIG. 11 is a bar graph comparing the yellowness index (YI) for anexemplary polycarbonate (LEXAN* polycarbonate grade PC135 having a meltvolume rate of 4) with the attached catalyst (“B”), and with theattached catalyst and a BPA purity of 99.65 wt %.

FIG. 12 is a graphical illustration of change in YI over time forvarious grades of LEXAN* polycarbonate formed with the new catalyst orwith the new BPA using a free hydroxyl concentration of less than 150ppm.

FIG. 13 is various chemical structures for materials discussed herein.

DETAILED DESCRIPTION

According to embodiments, polycarbonate compositions having enhancedoptical properties are disclosed, as well as their methods ofmanufacture and uses thereof, and articles made therefrom.

In accordance with an embodiment, and as further described below, theinventors have developed an interfacial process to manufacture acomposition comprising a polycarbonate, such as a BPA polycarbonate,with transmission levels higher than 90.0% at 2.5 millimeter (mm)thickness, and a YI lower than 1.5, with an increase in YI of less than2 during 2,000 hours of heat aging at 130° C. As used herein, YI ismeasured in accordance with ASTM D1925, while transmission is measuredin accordance with ASTM D-1003-00, Procedure A, measured, e.g., using aHAZE-GUARD DUAL from BYK-Gardner, using and integrating sphere(0°/diffuse geometry), wherein the spectral sensitivity conforms to theInternational Commission on Illumination (CIE) standard spectral valueunder standard lamp D65.

The enhanced optical properties can be achieved by employing in theinterfacial process a starting BPA monomer having both an organic purity(e.g., measured by HPLC of greater than or equal to 99.65 wt %) and asulfur level of less than or equal to 2 ppm. The organic purity can bedefined as 100 wt % minus the sum of known and unknown impuritiesdetected using ultraviolet (UV) (see HPLC method in Nowakowska et al.,Polish J. Appl. Chem., XI(3), 247-254 (1996)). The use of an end-cappingagent can be employed in the reaction such that the resultantcomposition comprising BPA polycarbonate comprises a free hydroxyl levelless than or equal to 150 ppm. Also, the sulfur level in the resultantcomposition (resin) can be less than or equal to 2 ppm, as measured by acommercially available Total Sulfur Analysis based on combustion andcoulometric detection.

It has been discovered that a surprising synergist effect can beachieved resulting in enhanced optical qualities (e.g., transmissionlevels higher than 90.0% at 2.5 mm thickness and a YI less than or equalto 1.5) by reacting, in an interfacial process (as opposed to a meltprocess), a low sulfur (less than or equal to 2 ppm) and highly pure(purity greater than or equal to 99.65 wt %) BPA starting material toform a BPA polycarbonate comprising a free hydroxyl level of less thanor equal to 150 ppm.

The disclosed interfacial process enhances the optical properties of BPApolycarbonate (e.g., Lexan* polycarbonate), upgrading transparency andimproving the durability of this transparency by lowering the blue lightabsorption.

While various types of polycarbonates could potentially be used inaccordance with embodiments and are described in detail below, ofparticular interest are BPA polycarbonates, such as Lexan* polycarbonate(Lexan* is a trademark of SABIC Innovative Plastics IP B. V.). Moreparticularly, according to embodiments, Lexan* polycarbonate can be usedfor a wide range of applications that make use of its interestingcombination of mechanical and optical properties. Its high impactresistance can make it an important component in numerous consumer goodssuch as mobile phones, MP3 players, computers, laptops, etc. Due to itstransparency, this BPA polycarbonate can find use in optical media,automotive lenses, roofing elements, greenhouses, photovoltaic devices,and safety glass. The developments in light emitting diode (LED)technology have led to significantly prolonged lifetimes for thelighting products to which this technology can be applied. This has ledto increased requirements on the durability of polycarbonates, inparticular on its optical properties. In other applications such asautomotive lighting, product developers may feel the need to designincreasingly complex shapes which cannot be made out of glass and forwhich the heat requirements are too stringent for polymethylmethacrylate (PMMA). Also in these applications polycarbonate is thematerial of choice, but the high transparency of PMMA and glass shouldbe approached as closely as possible.

Polycarbonate has the tendency to develop a yellow tint due to lightabsorption stretching into the blue regions of the spectrum (FIG. 1,line-R); a tint which gets worse upon heat aging. FIG. 1 is a graphdepicting transmission spectra of polycarbonates (transmission (%)versus wavelength (nm)). This tint can be compensated for through theaddition of colorants which absorb light in the yellow region to give aneutral tint (FIG. 1, line-B). Absorbing blue and yellow light lowersthe overall transmission of the material, see FIG. 2. FIG. 2 is a graphdepicting the yellowness and transmission of PC compared to PMMA andstandard uncoated glass (YI (−) versus transmission (%)). Withcolorants, it is possible to move within one of the ellipsoid areas,lowering yellowness at the expense of transmission. By making processimprovements, one can move from the darker area to the lighter one,lowering yellowness while gaining transmission. The inventors havedetermined that it would thus be desirable to have a colorless materialby preventing or removing the blue light absorption which will increasethe overall transmission (FIG. 1, dotted line-G).

As noted above, although BPA polycarbonates, such as Lexan*polycarbonates are of particular interest, various polycarbonates couldpotentially be employed in the embodiments disclosed herein. Forexample, in general, various types of polycarbonates that have arepeating structural background of the following formula:

can be utilized for embodiments encompassed by this disclosure.

The selection of a polycarbonate backbone of choice depends on manyfactors such as end use and other factors understood by one of ordinaryskill the art.

In one embodiment, the polycarbonates have repeating structuralcarbonate units of the formula (1):

wherein at least 60 percent of the total number of R¹ groups containsaromatic organic groups and the balance thereof are aliphatic,alicyclic, or aromatic groups.

In another embodiment, the polycarbonate is derived from bisphenol-A.

In another embodiment, each R¹ group is a divalent aromatic group, forexample derived from an aromatic dihydroxy compound of the formula (3):HO-A¹-Y¹-A²-OH  (3)wherein each of A¹ and A² is a monocyclic divalent arylene group, and Y¹is a single bond or a bridging group having one or two atoms thatseparate A¹ from A². In an exemplary embodiment, one atom separates A¹from A². In another embodiment, when each of A¹ and A² is phenylene, Y¹is para to each of the hydroxyl groups on the phenylenes. Illustrativenon-limiting examples of groups of this type are —O—, —S—, —S(O)—,—S(O)₂—, —C(O)—, methylene, cyclohexyl-methylene,2-[2.2.1]-bicycloheptylidene, ethylidene, isopropylidene,neopentylidene, cyclohexylidene, cyclopentadecylidene,cyclododecylidene, and adamantylidene. The bridging group Y¹ can be ahydrocarbon group or a saturated hydrocarbon group such as methylene,cyclohexylidene, or isopropylidene.

Included within the scope of formula (3) are bisphenol compounds ofgeneral formula (4):

wherein R^(a) and R^(b) each represent a halogen atom or a monovalenthydrocarbon group and can be the same or different; p and q are eachindependently integers of 0 to 4; and X^(a) represents a single bond orone of the groups of formulas (5) or (6):

wherein R^(c) and R^(d) are each independently hydrogen, C₁₋₁₂ alkyl,C₁₋₁₂ cycloalkyl, C₇₋₁₂ arylalkyl, C₁₋₁₂ heteroalkyl, or cyclic C₇₋₁₂heteroarylalkyl, and R^(e) is a divalent C₁₋₁₂ hydrocarbon group. Inparticular, R^(c) and R^(d) are each the same hydrogen or C₁₋₄ alkylgroup, specifically the same C₁₋₃ alkyl group, even more specifically,methyl.

In an embodiment, R^(c) and R^(d) taken together represent a C₃₋₂₀cyclic alkylene group or a heteroatom-containing C₃₋₂₀ cyclic alkylenegroup comprising carbon atoms and heteroatoms with a valency of two orgreater. These groups can be in the form of a single saturated orunsaturated ring, or a fused polycyclic ring system wherein the fusedrings are saturated, unsaturated, or aromatic. A specificheteroatom-containing cyclic alkylene group comprises at least oneheteroatom with a valency of 2 or greater, and at least two carbonatoms. Exemplary heteroatoms in the heteroatom-containing cyclicalkylene group include —O—, —S—, and —N(Z)—, where Z is a substituentgroup selected from hydrogen, hydroxy, C₁₋₁₂ alkyl, C₁₋₁₂ alkoxy, orC₁₋₁₂ acyl.

In a specific exemplary embodiment, X^(a) is a substituted C₃₋₁₈cycloalkylidene of the formula (7):

wherein each R^(r), R^(p), R^(q), and R^(t) is independently hydrogen,halogen, oxygen, or C₁₋₁₂ organic group; I is a direct bond, a carbon,or a divalent oxygen, sulfur, or —N(Z)— wherein Z is hydrogen, halogen,hydroxy, C₁₋₁₂ alkyl, C₁₋₁₂ alkoxy, or C₁₋₁₂ acyl; h is 0 to 2, j is 1or 2, i is an integer of 0 or 1, and k is an integer of 0 to 3, with theproviso that at least two of R^(r), R^(p), R^(q), and R^(t) takentogether are a fused cycloaliphatic, aromatic, or heteroaromatic ring.It will be understood that where the fused ring is aromatic, the ring asshown in formula (7) will have an unsaturated carbon-carbon linkagewhere the ring is fused. When k is 1 and i is 0, the ring as shown informula (7) contains 4 carbon atoms, when k is 2, the ring as showncontains 5 carbon atoms, and when k is 3, the ring contains 6 carbonatoms. In one embodiment, two adjacent groups (e.g., R^(q) and R^(t)taken together) form an aromatic group, and in another embodiment, R^(q)and R^(t) taken together form one aromatic group and R^(r) and R^(p)taken together form a second aromatic group.

When k is 3 and i is 0, bisphenols containing substituted orunsubstituted cyclohexane units are used, for example bisphenols offormula (8):

wherein each R^(f) is independently hydrogen, C₁₋₁₂ alkyl, or halogen;and each R^(g) is independently hydrogen or C₁₋₁₂ alkyl. Thesubstituents can be aliphatic or aromatic, straight chain, cyclic,bicyclic, branched, saturated, or unsaturated. Suchcyclohexane-containing bisphenols, for example the reaction product oftwo moles of a phenol with one mole of a hydrogenated isophorone, areuseful for making polycarbonate polymers with high glass transitiontemperatures and high heat distortion temperatures. Cyclohexyl bisphenolcontaining polycarbonates, or a combination comprising at least one ofthe foregoing with other bisphenol polycarbonates, are supplied by BayerCo. under the APEC* trade name.

Other useful dihydroxy compounds having the formula HO—R¹—OH includearomatic dihydroxy compounds of formula (9):

wherein each R^(h) is independently a halogen atom, a C₁₋₁₀ hydrocarbylsuch as a C₁₋₁₀ alkyl group, a halogen substituted C₁₋₁₀ hydrocarbylsuch as a halogen-substituted C₁₋₁₀ alkyl group, and n is 0 to 4. Thehalogen is usually bromine.

Some illustrative examples of dihydroxy compounds include the following:4,4′-dihydroxybiphenyl, 1,6-dihydroxynaphthalene,2,6-dihydroxynaphthalene, bis(4-hydroxyphenyl)methane,bis(4-hydroxyphenyl)diphenylmethane,bis(4-hydroxyphenyl)-1-naphthylmethane, 1,2-bis(4-hydroxyphenyl)ethane,1,1-bis(4-hydroxyphenyl)-1-phenylethane,2-(4-hydroxyphenyl)-2-(3-hydroxyphenyl)propane,bis(4-hydroxyphenyl)phenylmethane,2,2-bis(4-hydroxy-3-bromophenyl)propane, 1,1-bis(hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxyphenyl)isobutene,1,1-bis(4-hydroxyphenyl)cyclododecane,trans-2,3-bis(4-hydroxyphenyl)-2-butene,2,2-bis(4-hydroxyphenyl)adamantine, alpha,alpha′-bis(4-hydroxyphenyl)toluene, bis(4-hydroxyphenyl)acetonitrile,2,2-bis(3-methyl-4-hydroxyphenyl)propane,2,2-bis(3-ethyl-4-hydroxyphenyl)propane,2,2-bis(3-n-propyl-4-hydroxyphenyl)propane,2,2-bis(3-isopropyl-4-hydroxyphenyl)propane,2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane,2,2-bis(3-t-butyl-4-hydroxyphenyl)propane,2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane,2,2-bis(3-allyl-4-hydroxyphenyl)propane,2,2-bis(3-methoxy-4-hydroxyphenyl)propane,2,2-bis(4-hydroxyphenyl)hexafluoropropane,1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene,1,1-dibromo-2,2-bis(4-hydroxyphenyl)ethylene,1,1-dichloro-2,2-bis(5-phenoxy-4-hydroxyphenyl)ethylene,4,4′-dihydroxybenzophenone, 3,3-bis(4-hydroxyphenyl)-2-butanone,1,6-bis(4-hydroxyphenyl)-1,6-hexanedione, ethylene glycolbis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)ether,bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfoxide,bis(4-hydroxyphenyl)sulfone, 9,9 to bis(4-hydroxyphenyl)fluorine,2,7-dihydroxypyrene,6,6′-dihydroxy-3,3,3′,3′-tetramethylspiro(bis)indane (“spirobiindanebisphenol”), 3,3-bis(4-hydroxyphenyl)phthalide,2,6-dihydroxydibenzo-p-dioxin, 2,6-dihydroxythianthrene,2,7-dihydroxyphenoxathin, 2,7-dihydroxy-9,10-dimethylphenazine,3,6-dihydroxydibenzofuran, 3,6-dihydroxydibenzothiophene, and2,7-dihydroxycarbazole, resorcinol, substituted resorcinol compoundssuch as 5-methyl resorcinol, 5-ethyl resorcinol, 5-propyl resorcinol,5-butyl resorcinol, 5-t-butyl resorcinol, 5-phenyl resorcinol, 5-cumylresorcinol, 2,4,5,6-tetrafluoro resorcinol, 2,4,5,6-tetrabromoresorcinol, or the like; catechol; hydroquinone; substitutedhydroquinones such as 2-methyl hydroquinone, 2-ethyl hydroquinone,2-propyl hydroquinone, 2-butyl hydroquinone, 2-t-butyl hydroquinone,2-phenyl hydroquinone, 2-cumyl hydroquinone, 2,3,5,6-tetramethylhydroquinone, 2,3,5,6-tetra-t-butyl hydroquinone, 2,3,5,6-tetrafluorohydroquinone, 2,3,5,6-tetrabromo hydroquinone, and the like, as well ascombinations comprising at least one of the foregoing dihydroxycompounds.

Specific examples of bisphenol compounds that can be represented byformula (3) include 1,1-bis(4-hydroxyphenyl) methane,1,1-bis(4-hydroxyphenyl) ethane, 2,2-bis(4-hydroxyphenyl) propane(hereinafter “bisphenol-A” or “BPA”), 2,2-bis(4-hydroxyphenyl) butane,2,2-bis(4-hydroxyphenyl) octane, 1,1-bis(4-hydroxyphenyl) propane,1,1-bis(4-hydroxyphenyl) n-butane, 2,2-bis(4-hydroxy-1-methylphenyl)propane, 1,1-bis(4-hydroxy-t-butylphenyl) propane,3,3-bis(4-hydroxyphenyl) phthalimidine,2-phenyl-3,3-bis(4-hydroxyphenyl) phthalimidine (PPPBP), and1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane (DMBPC). Combinationscomprising at least one of the foregoing dihydroxy compounds can also beused.

“Polycarbonate” as used herein includes homopolycarbonates, copolymerscomprising different R¹ moieties in the carbonate (referred to herein as“copolycarbonates”), and copolymers comprising carbonate units and othertypes of polymer units, such as ester units. In one specific embodiment,the polycarbonate is a linear homopolymer or copolymer comprising unitsderived from bisphenol-A, in which each of A¹ and A² is p-phenylene andY¹ is isopropylidene in formula (3). More specifically, at least 60%,particularly at least 80% of the R¹ groups in the polycarbonate arederived from bisphenol-A.

Another specific type of copolymer is a polyester carbonate, also knownas a polyester-polycarbonate. Such copolymers further contain, inaddition to recurring carbonate chain units of the formula (1),repeating units of formula (10):

wherein D is a divalent group derived from a dihydroxy compound, and canbe, for example, a C₂₋₁₀ alkylene group, a C₆₋₂₀ alicyclic group, aC₆₋₂₀ aromatic group or a polyoxyalkylene group in which the alkylenegroups contain 2 to 6 carbon atoms, specifically 2, 3, or 4 carbonatoms; and T divalent group derived from a dicarboxylic acid, and canbe, for example, a C₂₋₁₀ alkylene group, a C₆₋₂₀ alicyclic group, aC₆₋₂₀ alkyl aromatic group, or a C₆₋₂₀ aromatic group.

In one embodiment, D is a C₂₋₃₀ alkylene group having a straight chain,branched chain, or cyclic (including polycyclic) structure. In anotherembodiment, D is derived from an aromatic dihydroxy compound of formula(4) above. In another embodiment, D is derived from an aromaticdihydroxy compound of formula (9) above.

Examples of aromatic dicarboxylic acids that can be used to prepare thepolyester units include isophthalic or terephthalic acid,1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether,4,4′-bisbenzoic acid, and combinations comprising at least one of theforegoing acids. Acids containing fused rings can also be present, suchas in 1,4-, 1,5-, or 2,6-naphthalenedicarboxylic acids. Specificdicarboxylic acids are terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexane dicarboxylic acid, or combinationsthereof. A specific dicarboxylic acid comprises a combination ofisophthalic acid and terephthalic acid wherein the weight ratio ofisophthalic acid to terephthalic acid is 91:9 to 2:98. In anotherspecific embodiment, D is a C₂₋₆ alkylene group and T is p-phenylene,m-phenylene, naphthalene, a divalent cycloaliphatic group, or acombination thereof. This class of polyester includes the poly(alkyleneterephthalates).

The molar ratio of ester units to carbonate units in the copolymers canvary broadly, for example 1:99 to 99:1, specifically 10:90 to 90:10,more specifically 25:75 to 75:25, depending on the desired properties ofthe final composition.

In a specific embodiment, the polyester unit of apolyester-polycarbonate can be derived from the reaction of acombination of isophthalic and terephthalic diacids (or derivativesthereof) with resorcinol. In another specific embodiment, the polyesterunit of a polyester-polycarbonate is derived from the reaction of acombination of isophthalic acid and terephthalic acid with bisphenol-A.In a specific embodiment, the polycarbonate units are derived frombisphenol-A. In another specific embodiment, the polycarbonate units arederived from resorcinol and bisphenol-A in a molar ratio of resorcinolcarbonate units to bisphenol-A carbonate units of 1:99 to 99:1.

A specific example of a polycarbonate-polyester is acopolycarbonate-polyester-polysiloxane terpolymer comprising carbonateunits of formula (1), ester units of formula (10), and polysiloxane(also referred to herein as “polydiorganosiloxane”) units of formula(11):

wherein each occurrence of R is same or different, and is a C₁₋₁₃monovalent organic group. For example, R may independently be a C₁₋₁₃alkyl group, C₁₋₁₃ alkoxy group, C₂₋₁₃ alkenyl group, C2-13 alkenyloxygroup, C₃₋₆ cycloalkyl group, C₃₋₆ cycloalkoxy group, C₆₋₁₄ aryl group,C₆₋₁₀ aryloxy group, C₇₋₁₃ arylalkyl group, C₇₋₁₃ arylalkoxy group,C₇₋₁₃ alkylaryl group, or C₇₋₁₃ alkylaryloxy group. The foregoing groupsmay be fully or partially halogenated with fluorine, chlorine, bromine,or iodine, or a combination thereof. Combinations of the foregoing Rgroups may be used in the same copolymer. In an embodiment, thepolysiloxane comprises R groups that have a minimum hydrocarbon content.In a specific embodiment, an R group with a minimum hydrocarbon contentis a methyl group.

The value of E in formula (11) may vary widely depending on the type andrelative amount of each component in the thermoplastic composition, thedesired properties of the composition, and like considerations. Herein,E can have an average value of 4 to 50. In an embodiment, E has anaverage value of 16 to 50, specifically 20 to 45, and more specifically25 to 45. In another embodiment, E has an average value of 4 to 15,specifically 5 to 15, more specifically 6 to 15, and still morespecifically 7 to 12.

In an embodiment, polydiorganosiloxane units are derived from dihydroxyaromatic compound of formula (12):

wherein E is as defined above; each R may independently be the same ordifferent, and is as defined above; and each Ar may independently be thesame or different, and is a substituted or unsubstituted C₆₋₃₀ arylenegroup, wherein the bonds are directly connected to an aromatic moiety.Exemplary Ar groups in formula (12) may be derived from a C₆₋₃₀dihydroxy aromatic compound, for example a dihydroxy aromatic compoundof formula (3), (4), (8), or (9) above. Combinations comprising at leastone of the foregoing dihydroxy aromatic compounds may also be used.Exemplary dihydroxy aromatic compounds are resorcinol (i.e.,1,3-dihydroxybenzene), 4-methyl-1,3-dihydroxybenzene,5-methyl-1,3-dihydroxybenzene, 4,6-dimethyl-1,3-dihydroxybenzene,1,4-dihydroxybenzene, 1,1-bis(4-hydroxyphenyl) methane,1,1-bis(4-hydroxyphenyl) ethane, 2,2-bis(4-hydroxyphenyl) propane,2,2-bis(4-hydroxyphenyl) butane, 2,2-bis(4-hydroxyphenyl) octane,1,1-bis(4-hydroxyphenyl) propane, 1,1-bis(4-hydroxyphenyl) n-butane,2,2-bis(4-hydroxy-1-methylphenyl) propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl sulfide), and1,1-bis(4-hydroxy-t-butylphenyl) propane. Combinations comprising atleast one of the foregoing dihydroxy compounds may also be used. In anembodiment, the dihydroxy aromatic compound is unsubstituted, or is notsubstituted with non-aromatic hydrocarbon-containing substituents suchas, for example, alkyl, alkoxy, or alkylene substituents.

In a specific embodiment, where Ar is derived from resorcinol, thepolydiorganosiloxane repeating units are derived from dihydroxy aromaticcompounds of formula (13):

or, where Ar is derived from bisphenol-A, from dihydroxy aromaticcompounds of formula (14):

wherein E is as defined above.

In another embodiment, polydiorganosiloxane units are derived fromdihydroxy aromatic compound of formula (15):

wherein R and E are as described above, and each occurrence of R² isindependently a divalent C₁₋₃₀ alkylene or C₇₋₃₀ arylene-alkylene, andwherein the polymerized polysiloxane unit is the reaction residue of itscorresponding dihydroxy aromatic compound. In a specific embodiment,where R² is C₇₋₃₀ arylene-alkylene, the polydiorganosiloxane units arederived from dihydroxy aromatic compound of formula (16):

wherein R and E are as defined above. Each R³ is independently adivalent C₂₋₈ aliphatic group. Each M may be the same or different, andmay be a halogen, cyano, nitro, C₁₋₈ alkylthio, C₁₋₈ alkyl, C₁₋₈ alkoxy,C₂₋₈ alkenyl, C₂₋₈ alkenyloxy group, C₃₋₈ cycloalkyl, C₃₋₈ cycloalkoxy,C₆₋₁₀ aryl, C₆₋₁₀ aryloxy, C₇₋₁₂ arylalkyl, C₇₋₁₂ arylalkoxy, C₇₋₁₂alkylaryl, or C₇₋₁₂ alkylaryloxy, wherein each n is independently 0, 1,2, 3, or 4.

In an embodiment, M is bromo or chloro, an alkyl group such as methyl,ethyl, or propyl, an alkoxy group such as methoxy, ethoxy, or propoxy,or an aryl group such as phenyl, chlorophenyl, or tolyl; R³ is adimethylene, trimethylene or tetramethylene group; and R is a C₁₋₈alkyl, haloalkyl such as trifluoropropyl, cyanoalkyl, or aryl such asphenyl, chlorophenyl or tolyl. In another embodiment, R is methyl, or acombination of methyl and trifluoropropyl, or a combination of methyland phenyl. In still another embodiment, M is methoxy, n is 0 or 1, R³is a divalent C₁₋₃ aliphatic group, and R is methyl.

In a specific embodiment, the polydiorganosiloxane units are derivedfrom a dihydroxy aromatic compound of formula (17):

wherein E is as described above.

In another specific embodiment, the polydiorganosiloxane units arederived from dihydroxy aromatic compound of formula (18):

wherein E is as defined above.

Dihydroxy polysiloxanes typically can be made by functionalizing asubstituted siloxane oligomer of formula (19):

wherein R and E are as previously defined, and Z is H, halogen (e.g.,Cl, Br, I), or carboxylate. Exemplary carboxylates include acetate,formate, benzoate, and the like. In an exemplary embodiment, where Z isH, compounds of formula (19) may be prepared by platinum catalyzedaddition with an aliphatically unsaturated monohydric phenol. Exemplaryaliphatically unsaturated monohydric phenols included, for example,eugenol, 2-allylphenol, 4-allylphenol, 4-allyl-2-methylphenol,4-allyl-2-phenylphenol, 4-allyl-2-bromophenol, 4-allyl-2-t-butoxyphenol,4-phenyl-2-allylphenol, 2-methyl-4-propenylphenol,2-allyl-4,6-dimethylphenol, 2-allyl-4-bromo-6-methylphenol,2-allyl-6-methoxy-4-methylphenol, and 2-allyl-4,6-dimethylphenol.Combinations comprising at least one of the foregoing may also be used.Where Z is halogen or carboxylate, functionalization may be accomplishedby reaction with a dihydroxy aromatic compound of formulas (3), (4),(8), (9), or a combination comprising at least one of the foregoingdihydroxy aromatic compounds. In an exemplary embodiment, compounds offormula (12) may be formed from an alpha,omega-bisacetoxypolydiorangonosiloxane and a dihydroxy aromatic compoundunder phase transfer conditions.

Specific copolycarbonate terpolymers include those with polycarbonateunits of formula (1) wherein R¹ is a C₆₋₃₀ arylene group, polysiloxaneunits derived from siloxane diols of formula (14), (17) or (18), andpolyester units wherein T is a C₆₋₃₀ arylene group. In an embodiment, Tis derived from isophthalic and/or terephthalic acid, or reactivechemical equivalents thereof. In another embodiment, R¹ is derived fromthe carbonate reaction product of a resorcinol of formula (9), or acombination of a resorcinol of formula (9) and a bisphenol of formula(4).

The relative amount of each type of unit in the foregoing terpolymerwill depend on the desired properties of the terpolymer, and are readilydetermined by one of ordinary skill in the art without undueexperimentation, using the guidelines provided herein. For example, thepolycarbonate-polyester-polysiloxane terpolymer can comprise siloxaneunits in an amount of 0.1 to 25 weight percent (wt %), specifically 0.2to 10 wt %, more specifically 0.2 to 6 wt %, even more specifically 0.2to 5 wt %, and still more specifically 0.25 to 2 wt %, based on thetotal weight of the polycarbonate-polyester-polysiloxane terpolymer,with the proviso that the siloxane units are provided by polysiloxaneunits covalently bonded in the polymer backbone of thepolycarbonate-polyester-polysiloxane terpolymer. Thepolycarbonate-polyester-polysiloxane terpolymer can further comprise 0.1to 49.85 wt % carbonate units, 50 to 99.7 wt % ester units, and 0.2 to 6wt % polysiloxane units, based on the total weight of the polysiloxaneunits, ester units, and carbonate units. Alternatively, thepolycarbonate-polyester-polysiloxane terpolymer comprises 0.25 to 2 wt %polysiloxane units, 60 to 96.75 wt % ester units, and 3.25 to 39.75 wt %carbonate units, based on the total weight of the polysiloxane units,ester units, and carbonate units.

Various types of thermoplastic compositions are encompassed byembodiments encompassed by this disclosure.

In one embodiment, the polycarbonate can be at least one of thefollowing: a homopolycarbonate derived from a bisphenol; acopolycarbonate derived from more than one bisphenol; and a copolymerderived from one or more bisphenols and having one or more aliphaticester units or aromatic ester units or siloxane units.

In another embodiment, in addition to the endcapped polycarbonatesdescribed above, the thermoplastic compositions can also comprise otherthermoplastic polymers, for example polyesters, polyamides, and otherpolycarbonate homopolymers and copolymers, includingpolycarbonate-polysiloxane copolymers and polyester carbonates, alsoknown as a polyester-polycarbonates, and polyesters. The polymercomponent of such compositions can comprise 1 to 99 wt %, specifically10 to 90, more specifically 20 to 80 wt % of the cyanophenyl endcappedpolycarbonate, with the remainder of the polymer component being otherpolymers.

In another embodiment, a second polycarbonate is formulated with thecomposition, wherein a second polycarbonate comprises a repeatingstructure of

wherein said second polycarbonate is different from said polycarbonateand wherein at least 60 percent of the total number of R¹ groups containaromatic organic groups and the balance thereof are aliphatic,alicyclic, or aromatic groups.

In another embodiment, the second polycarbonate is derived frombisphenol-A.

The polycarbonates according to embodiments can contain branchedpolycarbonate(s). Various types of branching agents can be utilized forembodiments encompassed by this disclosure.

Branched polycarbonate blocks can be prepared by adding a branchingagent during polymerization. These branching agents includepolyfunctional organic compounds containing at least three functionalgroups selected from hydroxyl, carboxyl, carboxylic anhydride,haloformyl, and mixtures of the foregoing functional groups. Specificexamples include trimellitic acid, trimellitic anhydride, trimellitictrichloride (TMTC), tris-p-hydroxy phenyl ethane (THPE),3,3-bis-(4-hydroxyphenyl)-oxindole (also known as isatin-bis-phenol),tris-phenol TC (1,3,5-tris((p-hydroxyphenyl)isopropyl)benzene),tris-phenol PA (4(4(1,1-bis(p-hydroxyphenyl)-ethyl) alpha,alpha-dimethyl benzyl)phenol), 4-chloroformyl phthalic anhydride,trimesic acid, and benzophenone tetracarboxylic acid. The branchingagents can be added at a level of 0.05 to 2.0 wt %. Mixtures comprisinglinear polycarbonates and branched polycarbonates can be used.

In some embodiments, a particular type of branching agent is used tocreate branched polycarbonate materials. These branched polycarbonatematerials have statistically more than two end groups. The branchingagent is added in an amount (relative to the bisphenol monomer) that issufficient to achieve the desired branching content, that is, more thantwo end groups. The molecular weight of the polymer may become very highupon addition of the branching agent and may lead to viscosity problemsduring phosgenation. Therefore, in some embodiments, an increase in theamount of the chain termination agent is used in the polymerization. Theamount of chain termination agent used when the particular branchingagent is used is generally higher than if only a chain termination agentalone is used. The amount of chain termination agent used is generallyabove 5 mole percent and less than 20 mole percent compared to thebisphenol monomer.

In some embodiments, the branching agent is a structure derived from atriacid trichloride of the formula (21)

wherein Z is hydrogen, a halogen, C₁₋₃ alkyl group, C₁₋₃ alkoxy group,C₇₋₁₂ arylalkyl, alkylaryl, or nitro group, and z is 0 to 3; or abranching agent derived from a reaction with a tri-substituted phenol ofthe formula (22)

wherein T is a C₁₋₂₀ alkyl group, C₁₋₂₀ alkyleneoxy group, C₇₋₁₂arylalkyl, or alkylaryl group, S is hydrogen, a halogen, C₁₋₃ alkylgroup, C₁₋₃ alkoxy group, C₇₋₁₂ arylalkyl, alkylaryl, or nitro group, sis 0 to 4.

In another embodiment, the branching agent is a structure having formula(23)

Examples of specific branching agents that are particularly effective inembodiments include trimellitic trichloride (TMTC), tris-p-hydroxyphenyl ethane (THPE) and isatin-bis-phenol. In one embodiment, informula (21), Z is hydrogen and z is 3. In another embodiment, informula (22), S is hydrogen, T is methyl and s is 4.

The relative amount of branching agents used in the manufacture of apolymer according to embodiments will depend on a number ofconsiderations, for example the type of R¹ groups, the amount ofcyanophenol, and the desired molecular weight of the polycarbonate. Ingeneral, the amount of branching agent is effective to provide about 0.1to 10 branching units per 100 R¹ units, specifically about 0.5 to 8branching units per 100 R¹ units, and more specifically about 0.75 to 5branching units per 100 R¹ units. For branching agents having formula(21), the amount of branching agent tri-ester groups are present in anamount of about 0.1 to 10 branching units per 100 R¹ units, specificallyabout 0.5 to 8 branching units per 100 R¹ units, and more specificallyabout 0.75 to 5 tri-ester units per 100 R¹ units. For branching agentshaving formula (22), the amount of branching agent tricarbonate groupsare present in an amount of about 0.1 to 10 branching units per 100 R¹units, specifically about 0.5 to 8 branching units per 100 R¹ units, andmore specifically about 0.75 to 5 tri-phenylcarbonate units per 100 R¹units. In some embodiments, a combination of two or more branchingagents may be used.

In one embodiment, the polycarbonate of a composition has a branchinglevel of greater than or equal to about 1%, or greater than or equal toabout 2%, or greater than or equal to about 3%, or about 1% to about 3%.

Various types of end-capping agents can be utilized for embodimentsencompassed by this disclosure.

In one embodiment, the end-capping agent is selected based upon themolecular weight of said polycarbonate and said branching level impartedby said branching agent.

In another embodiment, the end-capping agents are selected from at leastone of the following: phenol or a phenol containing one or moresubstitutions with at least one of the following: aliphatic groups,olefinic groups, aromatic groups, halogens, ester groups, and ethergroups.

In another embodiment, the end-capping agents are selected from at leastone of the following: phenol, para-t-butylphenol or para-cumylphenol.

Various types of additives, such as flame retardants, can be utilized inembodiments encompassed herein.

In one embodiment, the flame retardant additives include, for example,flame retardant salts such as alkali metal salts of perfluorinated C₁₋₁₆alkyl sulfonates such as potassium perfluorobutane sulfonate (Rimarsalt), potassium perfluoroctane sulfonate, tetraethylammoniumperfluorohexane sulfonate, potassium diphenylsulfone sulfonate (KSS),and the like; and salts formed by reacting for example an alkali metalor alkaline earth metal (for example lithium, sodium, potassium,magnesium, calcium and barium salts) and an inorganic acid complex salt,for example, an oxo-anion, such as alkali metal and alkaline-earth metalsalts of carbonic acid, such as Na₂CO₃, K₂CO₃, MgCO₃, CaCO₃, and BaCO₃or fluoro-anion complex such as Li₃AlF₆, BaSiF₆, KBF₄, K₃AlF₆, KAlF₄,K₂SiF₆, and/or Na₃AlF₆ or the like. Rimar salt and KSS, alone or incombination with other flame retardants, are particularly useful in thepolycarbonate compositions disclosed herein.

In another embodiment, the flame-retardants are selected from at leastone of the following: alkali metal salts of perfluorinated C₁₋₁₆ alkylsulfonates; potassium perfluorobutane sulfonate; potassiumperfluoroctane sulfonate; tetraethylammonium perfluorohexane sulfonate;and potassium diphenylsulfone sulfonate.

In another embodiment, the flame retardant is not a bromine or chlorinecontaining composition.

In another embodiment, the flame retardant additives include organiccompounds that include phosphorus, bromine, and/or chlorine.Non-brominated and non-chlorinated phosphorus-containing flameretardants can be used in certain applications for regulatory reasons,for example organic phosphates and organic compounds containingphosphorus-nitrogen bonds. One type of exemplary organic phosphate is anaromatic phosphate of the formula (GO)₃P═O, wherein each G isindependently an alkyl, cycloalkyl, aryl, alkylaryl, or arylalkyl group,provided that at least one G is an aromatic group. Two of the G groupscan be joined together to provide a cyclic group, for example, diphenylpentaerythritol diphosphate. Exemplary aromatic phosphates include,phenyl bis(dodecyl) phosphate, phenyl bis(neopentyl) phosphate, phenylbis(3,5,5′-trimethylhexyl) phosphate, ethyl diphenyl phosphate,2-ethylhexyl di(p-tolyl) phosphate, bis(2-ethylhexyl) p-tolyl phosphate,tritolyl phosphate, bis(2-ethylhexyl) phenyl phosphate, tri(nonylphenyl)phosphate, bis(dodecyl) p-tolyl phosphate, dibutyl phenyl phosphate,2-chloroethyl diphenyl phosphate, p-tolyl bis(2,5,5′-trimethylhexyl)phosphate, 2-ethylhexyl diphenyl phosphate, or the like. A specificaromatic phosphate is one in which each G is aromatic, for example,triphenyl phosphate, tricresyl phosphate, isopropylated triphenylphosphate, and the like.

Di- or poly-functional aromatic phosphorus-containing compounds are alsouseful, for example, compounds of the formulas below:

wherein each G¹ is independently a hydrocarbon having 1 to 30 carbonatoms; each G² is independently a hydrocarbon or hydrocarbonoxy having 1to 30 carbon atoms; each X is independently a bromine or chlorine; m is0 to 4, and n is 1 to 30. Exemplary di- or polyfunctional aromaticphosphorus-containing compounds include resorcinol tetraphenyldiphosphate (RDP), the bis(diphenyl) phosphate of hydroquinone and thebis(diphenyl) phosphate of bisphenol-A, respectively, their oligomericand polymeric counterparts, and the like.

Exemplary flame retardant additives containing phosphorus-nitrogen bondsinclude phosphonitrilic chloride, phosphorus ester amides, phosphoricacid amides, phosphonic acid amides, phosphinic acid amides,tris(aziridinyl) phosphine oxide.

Halogenated organic flame retardant compounds can also be used as flameretardants, for example halogenated flame retardant compounds of formula(20):

wherein R is a C₁₋₃₆ alkylene, alkylidene or cycloaliphatic linkage,e.g., methylene, ethylene, propylene, isopropylene, isopropylidene,butylene, isobutylene, amylene, cyclohexylene, cyclopentylidene, or thelike; or an oxygen ether, carbonyl, amine, or a sulfur-containinglinkage, e.g., sulfide, sulfoxide, sulfone, or the like. R can alsoconsist of two or more alkylene or alkylidene linkages connected by suchgroups as aromatic, amino, ether, carbonyl, sulfide, sulfoxide, sulfone,or the like.

Ar and Ar′ in formula (20) are each independently mono- orpolycarbocyclic aromatic groups such as phenylene, biphenylene,terphenylene, naphthylene, or the like

Y is an organic, inorganic, or organometallic radical, for example (1)halogen, e.g., chlorine, bromine, iodine, fluorine or (2) ether groupsof the general formula OB, wherein B is a monovalent hydrocarbon groupsimilar to X or (3) monovalent hydrocarbon groups of the typerepresented by R or (4) other substituents, e.g., nitro, cyano, and thelike, said substituents being essentially inert provided that there isgreater than or equal to one, specifically greater than or equal to two,halogen atoms per aryl nucleus.

When present, each X is independently a monovalent hydrocarbon group,for example an alkyl group such as methyl, ethyl, propyl, isopropyl,butyl, decyl, or the like; an aryl groups such as phenyl, naphthyl,biphenyl, xylyl, tolyl, or the like; and aralkyl group such as benzyl,ethylphenyl, or the like; a cycloaliphatic group such as cyclopentyl,cyclohexyl, or the like. The monovalent hydrocarbon group can itselfcontain inert substituents.

Each d is independently 1 to a maximum equivalent to the number ofreplaceable hydrogens substituted on the aromatic rings comprising Ar orAr′. Each e is independently 0 to a maximum equivalent to the number ofreplaceable hydrogens on R. Each a, b, and c is independently a wholenumber, including 0. When b is not 0, neither a nor c can be 0.Otherwise either a or c, but not both, can be 0. Where b is 0, thearomatic groups are joined by a direct carbon-carbon bond.

The hydroxyl and Y substituents on the aromatic groups, Ar and Ar′ canbe varied in the ortho, meta or para positions on the aromatic rings andthe groups can be in any possible geometric relationship with respect toone another.

Included within the scope of the above formula are bisphenols of whichthe following are representative: 2,2-bis-(3,5-dichlorophenyl)-propane;bis-(2-chlorophenyl)-methane; bis(2,6-dibromophenyl)-methane;1,1-bis-(4-iodophenyl)-ethane; 1,2-bis-(2,6-dichlorophenyl)-ethane;1,1-bis-(2-chloro-4-iodophenyl)ethane;1,1-bis-(2-chloro-4-methylphenyl)-ethane;1,1-bis-(3,5-dichlorophenyl)-ethane;2,2-bis-(3-phenyl-4-bromophenyl)-ethane;2,6-bis-(4,6-dichloronaphthyl)-propane;2,2-bis-(2,6-dichlorophenyl)-pentane;2,2-bis-(3,5-dibromophenyl)-hexane; bis-(4-chlorophenyl)-phenyl-methane;bis-(3,5-dichlorophenyl)-cyclohexylmethane;bis-(3-nitro-4-bromophenyl)-methane;bis-(4-hydroxy-2,6-dichloro-3-methoxyphenyl)-methane; and2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane 2,2bis-(3-bromo-4-hydroxyphenyl)-propane. Also included within the abovestructural formula are: 1,3-dichlorobenzene, 1,4-dibromobenzene,1,3-dichloro-4-hydroxybenzene, and biphenyls such as2,2′-dichlorobiphenyl, polybrominated 1,4-diphenoxybenzene,2,4′-dibromobiphenyl, and 2,4′-dichlorobiphenyl as well as decabromodiphenyl oxide, and the like.

Another useful class of flame retardant is the class of cyclic siloxaneshaving the general formula (R₂SiO)_(y) wherein R is a monovalenthydrocarbon or fluorinated hydrocarbon having from 1 to 18 carbon atomsand y is a number from 3 to 12. Examples of fluorinated hydrocarboninclude, but are not limited to, 3-fluoropropyl, 3,3,3-trifluoropropyl,5,5,5,4,4,3,3-heptafluoropentyl, fluorophenyl, difluorophenyl andtrifluorotolyl. Examples of exemplary cyclic siloxanes include, but arenot limited to, octamethylcyclotetrasiloxane,1,2,3,4-tetramethyl-1,2,3,4-tetravinylcyclotetrasiloxane,1,2,3,4-tetramethyl-1,2,3,4-tetraphenylcyclotetrasiloxane,octaethylcyclotetrasiloxane, octapropylcyclotetrasiloxane,octabutylcyclotetrasiloxane, decamethylcyclopentasiloxane,dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane,hexadecamethylcyclooctasiloxane, eicosamethylcyclodecasiloxane,octaphenylcyclotetrasiloxane, and the like. A particularly useful cyclicsiloxane is octaphenylcyclotetrasiloxane.

When present, the foregoing flame retardant additives are generallypresent in amounts of 0.01 to 10 wt %, more specifically 0.02 to 5 wt %,based on 100 parts by weight of the polymer component of thethermoplastic composition.

In another embodiment, the thermoplastic composition can further includean impact modifier(s), with the proviso that the additives are selectedso as to not significantly adversely affect the desired properties ofthe thermoplastic composition. Exemplary impact modifiers are typicallyhigh molecular weight elastomeric materials derived from olefins,monovinyl aromatic monomers, acrylic and methacrylic acids and theirester derivatives, as well as conjugated dienes. The polymers formedfrom conjugated dienes can be fully or partially hydrogenated. Theelastomeric materials can be in the form of homopolymers or copolymers,including random, block, radial block, graft, and core-shell copolymers.Combinations of impact modifiers can be used.

A specific type of impact modifier is an elastomer-modified graftcopolymer comprising (i) an elastomeric (i.e., rubbery) polymersubstrate having a glass transition temperature (T_(g)) less than 10°C., more specifically less than −10° C., or more specifically −40° to−80° C., and (ii) a rigid polymeric superstrate grafted to theelastomeric polymer substrate. Materials for use as the elastomericphase include, for example, conjugated diene rubbers, for examplepolybutadiene and polyisoprene; copolymers of a conjugated diene withless than 50 wt % of a copolymerizable monomer, for example amonovinylic compound such as styrene, acrylonitrile, n-butyl acrylate,or ethyl acrylate; olefin rubbers such as ethylene propylene copolymers(EPR) or ethylene-propylene-diene monomer rubbers (EPDM); ethylene-vinylacetate rubbers; silicone rubbers; elastomeric C₁₋₈ alkyl(meth)acrylates; elastomeric copolymers of C₁₋₈ alkyl (meth)acrylateswith butadiene and/or styrene; or combinations comprising at least oneof the foregoing elastomers. Materials for use as the rigid phaseinclude, for example, monovinyl aromatic monomers such as styrene andalpha-methyl styrene, and monovinylic monomers such as acrylonitrile,acrylic acid, methacrylic acid, and the C₁-C₆ esters of acrylic acid andmethacrylic acid, specifically methyl methacrylate. As used herein, theterm “(meth)acrylate” encompasses both acrylate and methacrylate groups.

Specific exemplary elastomer-modified graft copolymers include thoseformed from styrene-butadiene-styrene (SBS), styrene-butadiene rubber(SBR), styrene-ethylene-butadiene-styrene (SEBS), ABS(acrylonitrile-butadiene-styrene),acrylonitrile-ethylene-propylene-diene-styrene (AES),styrene-isoprene-styrene (SIS), methyl methacrylate-butadiene-styrene(MBS), and styrene-acrylonitrile (SAN).

Impact modifiers, when present, are generally present in amounts of 1 to30 wt %, based on 100 parts by weight of the polymer component of thethermoplastic composition.

According to an embodiment, the thermoplastic composition also caninclude various additives ordinarily incorporated in polycarbonatecompositions of this type, with the proviso that the additives areselected so as to not significantly adversely affect the desiredproperties of the polycarbonate, for example, transparency and flameretardance. Combinations of additives can be used. Such additives can bemixed at a suitable time during the mixing of the components for formingthe composition.

Various additives can be incorporated into the composition of mattersencompassed by embodiments disclosed herein.

In one embodiment, one or more additives are selected from at least oneof the following: UV stabilizing additives, thermal stabilizingadditives, mold release agents, colorants, organic and inorganicfillers, and gamma-stabilizing agents.

Possible fillers or reinforcing agents include, for example, silicatesand silica powders such as aluminum silicate (mullite), syntheticcalcium silicate, zirconium silicate, fused silica, crystalline silicagraphite, natural silica sand, or the like; boron powders such asboron-nitride powder, boron-silicate powders, or the like; oxides suchas TiO₂, aluminum oxide, magnesium oxide, or the like; calcium sulfate(as its anhydride, dihydrate or trihydrate); calcium carbonates such aschalk, limestone, marble, synthetic precipitated calcium carbonates, orthe like; talc, including fibrous, modular, needle shaped, lamellartalc, or the like; wollastonite; surface-treated wollastonite; glassspheres such as hollow and solid glass spheres, silicate spheres,cenospheres, aluminosilicate (armospheres), or the like; kaolin,including hard kaolin, soft kaolin, calcined kaolin, kaolin comprisingvarious coatings known in the art to facilitate compatibility with thepolycarbonate polymeric matrix, or the like; single crystal fibers or“whiskers” such as silicon carbide, alumina, boron carbide, iron,nickel, copper, or the like; fibers (including continuous and choppedfibers) such as asbestos, carbon fibers, glass fibers, such as E, A, C,ECR, R, S, D, or NE glasses, or the like; sulfides such as molybdenumsulfide, zinc sulfide or the like; barium compounds such as bariumtitanate, barium ferrite, barium sulfate, heavy spar, or the like;metals and metal oxides such as particulate or fibrous aluminum, bronze,zinc, copper and nickel or the like; flaked fillers such as glassflakes, flaked silicon carbide, aluminum diboride, aluminum flakes,steel flakes or the like; fibrous fillers, for example short inorganicfibers such as those derived from blends comprising at least one ofaluminum silicates, aluminum oxides, magnesium oxides, and calciumsulfate hemihydrate or the like; natural fillers and reinforcements,such as wood flour obtained by pulverizing wood, fibrous products suchas cellulose, cotton, sisal, jute, starch, cork flour, lignin, groundnut shells, corn, rice grain husks or the like; organic fillers such aspolytetrafluoroethylene; reinforcing organic fibrous fillers formed fromorganic polymers capable of forming fibers such as poly(ether ketone),polyimide, polybenzoxazole, poly(phenylene sulfide), polyesters,polyethylene, aromatic polyamides, aromatic polyimides, polyetherimides,polytetrafluoroethylene, acrylic resins, poly(vinyl alcohol) or thelike; as well as additional fillers and reinforcing agents such as mica,clay, feldspar, flue dust, fillite, quartz, quartzite, perlite, tripoli,diatomaceous earth, carbon black, or the like, or combinationscomprising at least one of the foregoing fillers or reinforcing agents.

The fillers and reinforcing agents can be coated with a layer ofmetallic material to facilitate conductivity, or surface treated withsilanes to improve adhesion and dispersion with the polycarbonatepolymeric matrix. In addition, the reinforcing fillers can be providedin the form of monofilament or multifilament fibers and can be usedindividually or in combination with other types of fiber, through, forexample, co-weaving or core/sheath, side-by-side, orange-type or matrixand fibril constructions, or by other methods known to one skilled inthe art of fiber manufacture. Exemplary co-woven structures include, forexample, glass fiber-carbon fiber, carbon fiber-aromatic polyimide(aramid) fiber, and aromatic polyimide fiberglass fiber or the like.Fibrous fillers can be supplied in the form of, for example, rovings,woven fibrous reinforcements, such as 0-90 degree fabrics or the like;non-woven fibrous reinforcements such as continuous strand mat, choppedstrand mat, tissues, papers and felts or the like; or three-dimensionalreinforcements such as braids. Fillers are generally used in amounts of0 to 80 parts by weight, based on 100 parts by weight of the polymercomponent of the composition.

Exemplary antioxidant additives include, for example, organophosphitessuch as tris(nonyl phenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite(e.g., “IRGAFOS 168” or “I-168”),bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearylpentaerythritol diphosphite or the like; alkylated monophenols orpolyphenols; alkylated reaction products of polyphenols with dienes,such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, or the like; butylated reaction products of para-cresol ordicyclopentadiene; alkylated hydroquinones; hydroxylated thiodiphenylethers; alkylidene-bisphenols; benzyl compounds; esters ofbeta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with monohydricor polyhydric alcohols; esters ofbeta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid withmonohydric or polyhydric alcohols; esters of thioalkyl or thioarylcompounds such as distearylthiopropionate, dilaurylthiopropionate,ditridecylthiodipropionate,octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionateor the like; amides ofbeta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid or the like, orcombinations comprising at least one of the foregoing antioxidants.Antioxidants are generally used in amounts of 0.0001 to 1 part byweight, based on 100 parts by weigh of the polymer component of thethermoplastic composition (excluding any filler).

Exemplary heat stabilizer additives include, for example,organophosphites such as triphenyl phosphite,tris-(2,6-dimethylphenyl)phosphite, tris-(mixed mono- anddi-nonylphenyl)phosphite or the like; phosphonates such asdimethylbenzene phosphonate or the like, phosphates such as trimethylphosphate, or the like, or combinations comprising at least one of theforegoing heat stabilizers. Heat stabilizers are generally used inamounts of 0.0001 to 1 part by weight, based on 100 parts by weight ofthe polymer component of the thermoplastic composition.

Light stabilizers and/or ultraviolet light (UV) absorbing additives canalso be used. Exemplary light stabilizer additives include, for example,benzotriazoles such as 2-(2-hydroxy-5-methylphenyl)benzotriazole,2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole and 2-hydroxy-4-n-octoxybenzophenone, or the like, or combinations comprising at least one ofthe foregoing light stabilizers. Light stabilizers are generally used inamounts of 0.0001 to 1 parts by weight, based on 100 parts by weight ofthe polymer component of the thermoplastic composition, according toembodiments.

Exemplary UV absorbing additives include for example,hydroxybenzophenones; hydroxybenzotriazoles; hydroxybenzotriazines;cyanoacrylates; oxanilides; benzoxazinones;2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol (CYASORR®5411); 2-hydroxy-4-n-octyloxybenzophenone (CYASORR® 531);2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phenol(CYASORB® 1164); 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one)(CYASORB® UV-3638);1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane (UVINUL® 3030);2,2′-(1,4-phenylene) bis(4H-3,1-benzoxazin-4-one);1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane;nano-size inorganic materials such as titanium oxide, cerium oxide, andzinc oxide, all with particle size less than or equal to 100 nanometers;or the like, or combinations comprising at least one of the foregoing UVabsorbers. UV absorbers are generally used in amounts of 0.0001 to 1part by weight, based on 100 parts by weight of the polymer component ofthe thermoplastic composition.

Plasticizers, lubricants, and/or mold release agents can also be used.There is considerable overlap among these types of materials, whichinclude, for example, phthalic acid esters such asdioctyl-4,5-epoxy-hexahydrophthalate;tris-(octoxycarbonylethyl)isocyanurate; tristearin; di- orpolyfunctional aromatic phosphates such as resorcinol tetraphenyldiphosphate (RDP), the bis(diphenyl) phosphate of hydroquinone and thebis(diphenyl) phosphate of bisphenol-A; poly-alpha-olefins; epoxidizedsoybean oil; silicones, including silicone oils; esters, for example,fatty acid esters such as alkyl stearyl esters, e.g., methyl stearate,stearyl stearate, pentaerythritol tetrastearate (PETS), and the like;combinations of methyl stearate and hydrophilic and hydrophobic nonionicsurfactants comprising polyethylene glycol polymers, polypropyleneglycol polymers, poly(ethylene glycol-co-propylene glycol) copolymers,or a combination comprising at least one of the foregoing glycolpolymers, e.g., methyl stearate and polyethylene-polypropylene glycolcopolymer in a suitable solvent; waxes such as beeswax, montan wax,paraffin wax, or the like. Such materials are generally used in amountsof 0.001 to 1 part by weight, specifically 0.01 to 0.75 part by weight,more specifically 0.1 to 0.5 part by weight, based on 100 parts byweight of the polymer component of the thermoplastic composition.

The term “antistatic agent” refers to monomeric, oligomeric, orpolymeric materials that can be processed into polymer resins and/orsprayed onto materials or articles to improve conductive properties andoverall physical performance. Examples of monomeric antistatic agentsinclude glycerol monostearate, glycerol distearate, glyceroltristearate, ethoxylated amines, primary, secondary and tertiary amines,ethoxylated alcohols, alkyl sulfates, alkylarylsulfates,alkylphosphates, alkylaminesulfates, alkyl sulfonate salts such assodium stearyl sulfonate, sodium dodecylbenzenesulfonate or the like,quaternary ammonium salts, quaternary ammonium resins, imidazolinederivatives, sorbitan esters, ethanolamides, betaines, or the like, orcombinations comprising at least one of the foregoing monomericantistatic agents.

Exemplary polymeric antistatic agents include certain polyesteramidespolyether-polyamide (polyetheramide) block copolymers,polyetheresteramide block copolymers, polyetheresters, or polyurethanes,each containing polyalkylene glycol moieties polyalkylene oxide unitssuch as polyethylene glycol, polypropylene glycol, polytetramethyleneglycol, and the like. Such polymeric antistatic agents are commerciallyavailable, for example PELESTAT* 6321 (Sanyo) or PEBAX* MH1657(Atofina), IRGASTAT* P18 and P22 (Ciba-Geigy). Other polymeric materialsthat can be used as antistatic agents are inherently conducting polymerssuch as polyaniline (commercially available as PANIPOL*EB from Panipol),polypyrrole and polythiophene (commercially available from Bayer), whichretain some of their intrinsic conductivity after melt processing atelevated temperatures. In one embodiment, carbon fibers, carbonnanofibers, carbon nanotubes, carbon black, or a combination comprisingat least one of the foregoing can be used in a polymeric resincontaining chemical antistatic agents to render the compositionelectrostatically dissipative. Antistatic agents are generally used inamounts of 0.0001 to 5 parts by weight, based on 100 parts by weight(pbw) of the polymer component of the thermoplastic composition.

Colorants such as pigment and/or dye additives can also be presentprovided they do not adversely affect, for example, any flame retardantperformance. Useful pigments can include, for example, inorganicpigments such as metal oxides and mixed metal oxides such as zinc oxide,titanium dioxides, iron oxides, or the like; sulfides such as zincsulfides, or the like; aluminates; sodium sulfo-silicates sulfates,chromates, or the like; carbon blacks; zinc ferrites; ultramarine blue;organic pigments such as azos, di-azos, quinacridones, perylenes,naphthalene tetracarboxylic acids, flavanthrones, isoindolinones,tetrachloroisoindolinones, anthraquinones, enthrones, dioxazines,phthalocyanines, and azo lakes; Pigment Red 101, Pigment Red 122,Pigment Red 149, Pigment Red 177, Pigment Red 179, Pigment Red 202,Pigment Violet 29, Pigment Blue 15, Pigment Blue 60, Pigment Green 7,Pigment Yellow 119, Pigment Yellow 147, Pigment Yellow 150, and PigmentBrown 24; or combinations comprising at least one of the foregoingpigments. Pigments are generally used in amounts of 0.01 to 10 parts byweight, based on 100 parts by weight of the polymer component of thethermoplastic composition.

Exemplary dyes are generally organic materials and include, for example,coumarin dyes such as coumarin 460 (blue), coumarin 6 (green), nile redor the like; lanthanide complexes; hydrocarbon and substitutedhydrocarbon dyes; polycyclic aromatic hydrocarbon dyes; scintillationdyes such as oxazole or oxadiazole dyes; aryl- or heteroaryl-substitutedpoly (C2-8) olefin dyes; carbocyanine dyes; indanthrone dyes;phthalocyanine dyes; oxazine dyes; carbostyryl dyes;napthalenetetracarboxylic acid dyes; porphyrin dyes; bis(styryl)biphenyldyes; acridine dyes; anthraquinone dyes; cyanine dyes; methine dyes;arylmethane dyes; azo dyes; indigoid dyes, thioindigoid dyes, diazoniumdyes; nitro dyes; quinone imine dyes; aminoketone dyes; tetrazoliumdyes; thiazole dyes; perylene dyes, perinone dyes;bis-benzoxazolylthiophene (BBOT); triarylmethane dyes; xanthene dyes;thioxanthene dyes; naphthalimide dyes; lactone dyes; fluorophores suchas anti-stokes shift dyes which absorb in the near infrared wavelengthand emit in the visible wavelength, or the like; luminescent dyes suchas 7-amino-4-methylcoumarin;3-(2′-benzothiazolyl)-7-diethylaminocoumarin;2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole;2,5-bis-(4-biphenylyl)-oxazole; 2,2′-dimethyl-p-quaterphenyl;2,2-dimethyl-p-terphenyl; 3,5,3″″,5″″-tetra-t-butyl-p-quinquephenyl;2,5-diphenylfuran; 2,5-diphenyloxazole; 4,4′-diphenylstilbene;4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran;1,1′-diethyl-2,2′-carbocyanine iodide;3,3′-diethyl-4,4′,5,5′-dibenzothiatricarbocyanine iodide;7-dimethylamino-1-methyl-4-methoxy-8-azaquinolone-2;7-dimethylamino-4-methylquinolone-2;2-(4-(4-dimethylaminophenyl)-1,3-butadienyl)-3-ethylbenzothiazoliumperchlorate; 3-diethylamino-7-diethyliminophenoxazonium perchlorate;2-(1-naphthyl)-5-phenyloxazole; 2,2′-p-phenylen-bis(5-phenyloxazole);rhodamine 700; rhodamine 800; pyrene, chrysene, rubrene, coronene, orthe like; or combinations comprising at least one of the foregoing dyes.Dyes are generally used in amounts of 0.01 to 10 parts by weight, basedon 100 parts by weight of the polymer component of the thermoplasticcomposition.

Where a foam is desired, useful blowing agents include, for example, lowboiling halohydrocarbons and those that generate carbon dioxide; blowingagents that are solid at room temperature and when heated totemperatures higher than their decomposition temperature, generate gasessuch as nitrogen, carbon dioxide, and ammonia gas, such asazodicarbonamide, metal salts of azodicarbonamide, 4,4′oxybis(benzenesulfonylhydrazide), sodium bicarbonate, ammoniumcarbonate, or the like, or combinations comprising at least one of theforegoing blowing agents. Blowing agents are generally used in amountsof 0.01 to 20 parts by weight, based on 100 parts by weight of thepolymer component of the thermoplastic composition.

Anti-drip agents can also be used in the thermoplastic compositionaccording to embodiments, for example a fibril forming or non-fibrilforming fluoropolymer such as polytetrafluoroethylene (PTFE). Theanti-drip agent can be encapsulated by a rigid copolymer as describedabove, for example styrene-acrylonitrile copolymer (SAN). PTFEencapsulated in SAN is known as TSAN. Encapsulated fluoropolymers can bemade by polymerizing the encapsulating polymer in the presence of thefluoropolymer, for example an aqueous dispersion. TSAN can providesignificant advantages over PTFE, in that TSAN can be more readilydispersed in the composition. An exemplary TSAN can comprise 50 wt %PTFE and 50 wt % SAN, based on the total weight of the encapsulatedfluoropolymer. The SAN can comprise, for example, 75 wt % styrene and 25wt % acrylonitrile based on the total weight of the copolymer.Alternatively, the fluoropolymer can be pre-blended in some manner witha second polymer, such as for, example, an aromatic polycarbonate or SANto form an agglomerated material for use as an anti-drip agent. Eithermethod can be used to produce an encapsulated fluoropolymer. Antidripagents are generally used in amounts of 0.1 to 5 percent by weight,based on 100 parts by weight of the polymer component of thethermoplastic composition.

Radiation stabilizers can also be present, specifically gamma-radiationstabilizers. Exemplary gamma-radiation stabilizers include alkylenepolyols such as ethylene glycol, propylene glycol, 1,3-propanediol,1,2-butanediol, 1,4-butanediol, meso-2,3-butanediol, 1,2-pentanediol,2,3-pentanediol, 1,4-pentanediol, 1,4-hexandiol, and the like;cycloalkylene polyols such as 1,2-cyclopentanediol, 1,2-cyclohexanediol,and the like; branched alkylenepolyols such as2,3-dimethyl-2,3-butanediol (pinacol), and the like, as well asalkoxy-substituted cyclic or acyclic alkanes. Unsaturated alkenols arealso useful, examples of which include 4-methyl-4-penten-2-ol,3-methyl-pentene-3-ol, 2-methyl-4-penten-2-ol, 2,4-dimethyl-4-pene-2-ol,and 9 to decen-1-ol, as well as tertiary alcohols that have at least onehydroxy substituted tertiary carbon, for example2-methyl-2,4-pentanediol (hexylene glycol), 2-phenyl-2-butanol,3-hydroxy-3-methyl-2-butanone, 2-phenyl-2-butanol, and the like, andcyclic tertiary alcohols such as 1-hydroxy-1-methyl-cyclohexane. Certainhydroxymethyl aromatic compounds that have hydroxy substitution on asaturated carbon attached to an unsaturated carbon in an aromatic ringcan also be used. The hydroxy-substituted saturated carbon can be amethylol group (—CH₂OH) or it can be a member of a more complexhydrocarbon group such as —CR⁴HOH or —CR⁴OH wherein R⁴ is a complex or asimple hydrocarbon. Specific hydroxy methyl aromatic compounds includebenzhydrol, 1,3-benzenedimethanol, benzyl alcohol, 4-benzyloxy benzylalcohol and benzyl benzyl alcohol. 2-Methyl-2,4-pentanediol,polyethylene glycol, and polypropylene glycol are often used forgamma-radiation stabilization. Gamma-radiation stabilizing compounds aretypically used in amounts of 0.1 to 10 parts by weight based on 100parts by weight of the polymer component of the thermoplasticcomposition.

Thermoplastic compositions according to embodiments can be manufacturedby various methods. For example, the desired constituents such as, forexample, polycarbonate, flame retardant, impact modifier (if present),and/or other optional components can be first blended in aHENSCHEL-Mixer* high speed mixer. Other low shear processes, includingbut not limited to hand mixing, can also accomplish this blending. Theblend is then fed into the throat of a single or twin-screw extruder viaa hopper. Alternatively, at least one of the components can beincorporated into the composition by feeding directly into the extruderat the throat and/or downstream through a sidestuffer. Additives canalso be compounded into a masterbatch with a desired polymeric resin andfed into the extruder. The extruder is generally operated at atemperature higher than that necessary to cause the composition to flow.The extrudate is immediately quenched in a water batch and pelletized.The pellets, so prepared, when cutting the extrudate can be one-fourthinch long or less as desired. Such pellets can be used for subsequentmolding, shaping, or forming.

In some embodiments described above, the onset of high-temperaturecross-linking can be controlled by adjusting the molecular weight of theend-capped polycarbonate or by the addition of certain flame retardantsalts, in particular alkali metal salts of perfluorinated C₁₋₁₆ alkylsulfonates. In one embodiment, the addition of an inorganic flameretardant (e.g., KSS) increases the temperature of the onset ofcross-linking/branching in the polycarbonate by 20 to 80° C.,specifically 40 to 60° C.

Shaped, formed, or molded articles comprising the thermoplasticcompositions are also provided, according to embodiments. Thethermoplastic compositions can be molded into useful shaped articles bya variety of means such as injection molding, extrusion, rotationalmolding, blow molding and thermoforming to form articles such as, forexample, computer and business machine housings such as housings formonitors, handheld electronic device housings such as housings for cellphones, electrical connectors, and components of lighting fixtures,ornaments, home appliances, roofs, greenhouses, sun rooms, swimming poolenclosures, thin walled articles such as housing for electronic devicesand the like. Additional examples of articles that can be formed fromthe compositions include electrical parts, such as relays, andenclosures, consumer electronics such as enclosures and parts forlaptops, desktops, docking stations, personal digital assistants (PDAs),digital cameras, desktops, and telecommunications parts such as partsfor base station terminals. Further examples of articles that can beformed from compositions include light guides, light guide panels,lenses, covers, sheets, films, and the like, e.g., LED lenses, LEDcovers, and so forth.

Interfacial Polymerization

In accordance with embodiments, polycarbonates having enhanced opticalqualities can be manufactured by an interfacial polymerization process.Although the reaction conditions for interfacial polymerization canvary, an exemplary process generally involves dissolving or dispersing adihydric phenol reactant in aqueous caustic soda or potash, adding theresulting mixture to a water-immiscible solvent medium, and contactingthe reactants with a carbonate precursor in the presence of a catalystsuch as, for example, triethylamine or a phase transfer catalyst, undercontrolled pH conditions, e.g., 8 to 11. The most commonly used waterimmiscible solvents include methylene chloride, 1,2-dichloroethane,chlorobenzene, toluene, and the like.

Exemplary carbonate precursors include, for example, a carbonyl halidesuch as carbonyl bromide or carbonyl chloride, or a haloformate such asa bishaloformates of a dihydric phenol (e.g., the bischloroformates ofbisphenol-A, hydroquinone, or the like) or a glycol (e.g., thebishaloformate of ethylene glycol, neopentyl glycol, polyethyleneglycol, or the like). Combinations comprising at least one of theforegoing types of carbonate precursors can also be used. In anexemplary embodiment, an interfacial polymerization reaction to formcarbonate linkages uses phosgene as a carbonate precursor, and isreferred to as a phosgenation reaction.

Among the phase transfer catalysts that can be used are catalysts of theformula (R₃)₄Q+X, wherein each R₃ is the same or different, and is aC₁₋₁₀ alkyl group; Q is a nitrogen or phosphorus atom; and X is ahalogen atom or a C₁₋₈ alkoxy group or C₆₋₁₈ aryloxy group. Exemplaryphase transfer catalysts include, for example, [CH₃(CH₂)₃]₄NX,[CH₃(CH₂)₃]₄PX, [CH₃(CH₂)₅]₄NX, [CH₃(CH₂)₆]₄NX, [CH₃(CH₂)₄]₄NX,CH₃[CH₃(CH₂)₃]₃NX, and CH₃[CH₃(CH₂)₂]₃NX, wherein X is Cl—, Br—, a C₁₋₈alkoxy group or a C₆₋₁₈ aryloxy group. An effective amount of a phasetransfer catalyst can be 0.1 to 10 wt % based on the weight of bisphenolin the phosgenation mixture. In another embodiment, an effective amountof phase transfer catalyst can be 0.5 to 2 wt % based on the weight ofbisphenol in the phosgenation mixture.

In one embodiment, the polycarbonate encompassed by this disclosure ismade by an interfacial polymerization process. One of ordinary skill inthe art would be able to carry out an interfacial process without undueexperimentation.

In another embodiment, the polycarbonate encompassed by this disclosureexcludes the utilization of a melt polymerization process to make atleast one of said polycarbonates.

Protocols may be adjusted so as to obtain a desired product within thescope of the disclosure and this can be done without undueexperimentation. A desired product is in one embodiment to achieve amolded article of the composition having a transmission level higherthan 90.0%, as measured by ASTM D1003, at 2.5 mm thickness and a YIlower than 1.5, as measured by ASTM D1925, with an increase in YI lowerthan 2 during 2000 hours of heat aging at 130° C. made by an interfacialprocess.

Embodiments are further illustrated by the following non-limitingexample/experimentation.

EXAMPLE

In order to test the effect of process parameters on resin color, allresins were tested in a simple, fixed formulation with only 0.05%tris(di-t-butylphenyl)phosphite. Such a formulation may not give optimalresults but allows differences in resin color to be observed. Granulatewas molded into 2.5 mm thickness color plaques which were used for colormeasurements. Transmission was measured on a Gardner Dual Hazeguardaccording to ASTM D1003 as disclosed above. Yellowness Index (YI) wascalculated from the absorption spectrum from a MacBeth 9000A accordingto ASTM D1925. Heat aging was done by placing color plaques in an ovenat 130° C. Color was measured at regular intervals over a period of5,000 hours (hrs).

It is noted that in addition to the afore-referenced heat stabilizertris(di-t-butylphenyl)phosphite (Irgafos 168), the inventors havedetermined that triphenyl phosphine (TPP) and Octadecyl3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Ultranxo 1076) also canbe effective, according to embodiments.

PC resin was depolymerized by adding 3 ml of tetrahydrofuran and 3milliliters (ml) of 10% w KOH in methanol to about 200 mg of resin orplastic. After shaking the solution for 60 minutes, the carbonateprecipitate was dissolved by adding 3 ml glacial acetic acid. Theresulting mixture was analyzed using a method similar to the onedescribed by J. Poskrobko et al., Journal of Chromatography A., 883,291-297 (2000), which is herein incorporated by reference. Note that theresults are essentially the sum of any residual, unreacted monomer andimpurities that are in the plastic and those that have reacted and havebeen incorporated in the chain.

BPX-1 was synthesized according to a procedure by Nowakowska et al.,Polish J. Appl. Chem. Xl(3), 247-254 (1996) and 9,9′ Dimethyxanthene(DMX) 96% was purchased from Sigma-Aldrich and used without any furtherpurification.

4-(4′-hydroxyphenyl)2,2,4-trimethylchroman (chroman), was prepared fromthe melted mixture of mesityl oxide and phenol. The mixture, containingthe excess of phenol was saturated with dry hydrogen chloride and leftfor 48 h at room temperature. The crude product was collected byfiltration and crystallized several times from toluene.

Spiking experiments of impurities were conducted in a pilot facility forinterfacial PC polymerization at 5 kg scale. Five batches were made ateach setting.

Results and Discussion

In an initial phase of this study, samples were collected across thebisphenol-A (BPA) monomer plant, the resin plant and the finishingfacility.

The BPA plant transforms phenol and acetone into BPA in an acidcatalyzed process. The resulting crude mixture of BPA, Phenol andby-products is subjected to a series of purification steps to yield BPAcrystals of the required purity.

In the resin plant, BPA and phosgene are reacted in the presence ofwater and dichloromethane (DCM) while the pH is kept high through theaddition of caustic. The result is a mixture containing PC resindissolved in DCM and brine. The organic solution goes through washingand purification steps and is dried to isolate the PC resin.

Finally the finishing plant extrudes the resin into granulates whileadding additives such as heat stabilizers, colorants, UV stabilizers andthe like.

A method was developed which allows impurities that are formed duringBPA synthesis to be traced back during all stages of making and usingthe polycarbonate and derived products, according to embodiments. A milddepolymerization procedure destroys carbonate and ester linkages andrestores the BPA monomer together with its impurities, which can then beanalyzed. The method can be applied to plant streams, resin powder,granulate or molded products including items taken from the market forcompetitive analyses.

Samples were taken in such a way that monomer, resin and granulatesamples would match one another, i.e. the monomer sample would be theone used to make the resin sample and the resin sample would be thematerial that was used in generating the plastic granulate. Twenty ofsuch sample sets were taken. Every sample was subjected to various teststo determine metal and ion contamination levels, organic purity, polymerend groups, etc. Finally, all of the analytical results were inspectedfor correlation to the color and transmission of molded plaques of thegranulate.

The results of this baseline study are summarized in Table 1, whichlists those measured properties, which were found to give astatistically relevant correlation to YI.

Table 1 set forth below discloses sample properties correlated toyellowness index.

TABLE 1 Initial color Heat aged color BPA BPX-1, chroman,spirobisindane, BPX-2, BPX-2 process DMX BPA organic purity BPA organicpurity sum of unknowns Resin resin oligomers resin oligomers processresidual ¹PCP, BPA residual PCP, BPA OH endgroups ortho OH groups Cl⁻,Na⁺, Ca⁺⁺, Fe³⁺, Ni⁺⁺, Cu⁺⁺, Zn⁺⁺ ¹para-cumylphenol

Table 2 sets forth below shows the average percent change in organicimpurities during plant processes. Only those numbers are reported whichare statistically significantly different from zero in the sample set.Species which are constant along the process are not reported therein.

TABLE 2 STD ABU heat reaction extrusion molding molding ageing Phenol+36 IPP +76 opBPA −11 −11 −8 BPX-1 −9 −8 −15 SBI +53 +59 BPX-2 −32 −31DMX −54 unknowns −66 +240 +305 +210

During reaction, the concentration of most impurities does not change.This is also not expected since all of these impurities have at leastone para-substituted OH group, which will react in a similar manner asBPA and result in incorporation in the polymer backbone. Besides, if anynew impurities are formed during the reaction at low temperature andhigh pH, it is unlikely that these will have a similar nature as thoseformed in an acidic environment at high temperatures. Most of theimpurities being constant indicates the applicability of this method.IPP (4-isopropenyl phenol) is the only species going up during the resinreaction and unknowns are going down. The latter can be explained by thewashing out of unreactive impurities during the resin cleaning steps.During extrusion, no significant changes in impurity levels take place.A more significant heat input is given to the materials during molding.Both during standard and abusive molding the levels of spirobisindane(SBI) and unknowns go up.

SBI is utilized as a monomer for polycarbonates with specific opticalproperties and enhanced glass transition temperature. Although polymerswith high levels of SBI do not have the same color stability as BPAbased polycarbonate, this compound is not expected to be a significantfactor in discoloration at trace levels. A considerable effort wasundertaken in looking at the peaks of individual unknown species,correlating them to color and trying to identify their structure. Thishas not led to the identification of a color body, unfortunately. Ratherthan looking at what is formed during molding and heat aging, it may beinteresting to look at what disappears. Both opBPA and BPX-1 arecomponents whose concentration decreases as color increases. In earlierreports opBPA or BPX-1 have never been suspect with regard todiscoloration. Their ortho OH groups have been considered mostlyharmless.

Based on the results of the correlations (Table 1), as well as theparticular profiles of opBPA and BPX-1 along the process (Table 2), itwas decided to run a number of polymerization experiments with specificimpurities independently spiked in at various concentrations. BPX-1,chroman and DMX were synthesized and isolated for this purpose. opBPAwas expected to behave in a comparable manner to BPX-1 due to thesimilarity of the structure (FIG. 3) and in concentration profile (Table2) and was not tested. FIG. 3 is a schematic illustration of selectedBPA impurities potentially related to color.

Chroman and DMX were spiked at four levels in the range of 100 to 1,000ppm relative to BPA. BPX-1 was spiked at 5 levels in the range of 200 to2,000 ppm. High purity BPA (99.92 wt %) was used for the polymerizationsto minimize the effects of other impurities on the final color.Reference samples without any spiked impurity were generated forcomparison. The initial color results had YI in the range of 1.5 to 2.0,but none of the variation was correlated to the spiked impurities. Theresults for the color shift upon 2,000 hours of heat aging are shown inFIG. 4. In particular, FIG. 4 shows changes in YI after 2,000 hours,heat aging at 130C.° as a function of spiking level of three differentimpurities (delta YI(−) versus spiking level (ppm).

The profiles for DMX and chroman are flat indicating these species arenot related to color stability. However, BPX-1 clearly increasesyellowness in the material after aging. This relationship between BPX-1and color stability only holds if the BPX-1 is spiked in a fixed, highpurity BPA. A data point for a sample derived from a regular quality ofBPA is plotted at its BPX-1 level of 150 ppm, but clearly there areother components in this sample which further increase thediscoloration. A second datapoint based on yet another BPA sample ofdifferent quality is placed at 400 ppm and δYI of 9.2, off the scale ofthe graph.

If BPX-1 degradation lies at the root of this discoloration, it can behypothesized that a scission reaction takes places that splits the BPX-1unit into a ppBPA unit and an IPP unit and that this IPP unit leads tocolored by products. Note that these units are not present in thematerial in the form in which they are presented in FIG. 3, but havereacted to their carbonate equivalent in-chain units. Likewise, then,opBPA can undergo a scission reaction to give phenol and IPP. Indeed, ifall datapoints are plotted as a function of the total level of opBPA andBPX-1 together, then a straight line is found (FIG. 5). FIG. 5 is agraph depicting the change in YI after 2,000 hours, heat aging at 130°C. as a function of the summed level of BPX-1 and opBPA as determinedanalytically (delta YI versus BPX-1+opBPA (ppm).

Note that the standard quality BPA dataset in this plot is based onsamples from three different BPA sources with varying quality levelspolymerized at pilot plant and commercial scale in three differentfacilities. Both samples which have been spiked as well as those inwhich the opBPA and BPX-1 components are present as the residuals fromBPA synthesis fall on the same line, which justifies the conclusion thatthese species lie at the origin of discoloration during heat aging andare not just correlated to discoloration in a non-causal fashion.

Interestingly, extrapolating the fitted line shows that in absence ofBPX-1 and opBPA, the discoloration would be reduced to δYI 0.5, which isonly a small fraction of the discoloration observed in the samplesderived from regular BPA, meaning that these two components are the maincontributors to discoloration.

Knowing which monomer impurities are detrimental to color stability is agood thing; the downside however is that opBPA is the most prominentimpurity that is formed during BPA synthesis and not a component whoseformation can be easily prevented in reaction or which is easily reducedin a selective way during in downstream purification steps. Therefore,improving the purification steps for BPA in a general sense proves themore cost effective way of improving resin color stability.

Besides this work on BPA impurities, further efforts were undertaken towork on the overall resin manufacturing process parameters (Table 1) andon formulation and compounding aspects to produce the final granulatedproduct. The advantages of this combined approach become apparent inFIG. 6. FIG. 6 is a graph depicting implementation of the describedprocess improvements combined with an optimized formulation improved thePC grade (delta YI(−) versus time (hours)).

Improving the manufacturing processes leads to a more sustainableperformance gain than what can be achieved through color stabilizing andcompensating additives alone. Additives may lose their effectivenessover time as can be seen in the product of ‘A’, that suddenly developscolor in an accelerated way after 1,000 hours (hrs) of aging. Both ourmaterials as well as the product of ‘B’ exhibit a predictable agingbehavior and with the improvements that we have implemented, our PCproducts offer state of the art performance.

It has been shown that the major source of color instability lies asearly in the manufacturing process as during monomer synthesis. Thecombined efforts of process improvement and product development have ledto products which combine a high light transmission, low color andexcellent retention of these properties in heat aging which makes themwell suited for applications in which long lifetimes are required suchas LED bulbs and lenses and those in which long path lengths are usedsuch as lightguides.

It is noted that the afore-described experimental results regardingLexan* polycarbonate is particularly advantageous in that Lexan*polycarbonate has excellent mechanical properties, which combined withits inherent transparency, make it the material of choice for lightingapplications such as lenses, lightguides and bulbs, as well asconstruction of roofing, greenhouses, verandas, and so forth. With theadvent of LED technology, the functional lifetime of lighting productshas increased impressively and will further expand in the years to come.Also, in construction application, durability is important. Plasticswill age, however, under the influence of heat, light and time, causingreduced light transmission and color changes. The inventors have hereinaddressed the above concerns and others, according to embodiments, toexplain the factors such as BPA purity level, sulfur level, hydroxylevel, type of process employed (interfacial) that can determine theoptical material performance. The inventors have advantageouslydetermined how optimization of such parameters during monomer and resinproduction can lead to further enhancement of color and color stabilityof the resulting plastic.

As further shown in Table 3, the polymerization type and BPA purity candictate heat aging color stability. Table 3 depicts YI (2000 hours, 130°C. and BPA purity (%)). A higher purity BPA can lead to 85% reduction ofdiscoloration.

TABLE 3 YI (2000 hrs resin process BPA organic purity @ 130° C.)Interfacial 99.45 13.3 Interfacial 99.51 13.0 Interfacial 99.63 10.7Interfacial 99.78 7.3 Melt 99.78 15.5 Melt 99.77 16.1 Melt 99.78 19.1

FIG. 7 is an exemplary chemical formula illustrating the formation ofBPA; the reaction is catalyzed through either a soluble organic thiolcontaining acidic compound. (referred to as ‘old catalyst’ or aninsoluble resin with acidic and thiol functionality which is insolublein BPA and the reaction mixture of BPA synthesis.

The catalyst can be attached to an insoluble resin for the reduction ofsulfur in BPA, e.g., down to less than 0.5 ppm, which resulted in asignificant reduction in YI (e.g., from greater than 1.4, specificallyup to 1.8, down to less than 1.4 and even down to 1.2).

FIG. 9 is a bar graph comparing the yellowness index (YI) for anexemplary polycarbonate (LEXAN* polycarbonate grade PC175 having a meltvolume rate of 30) with the bulk catalyst (bars “A”), the attachedcatalyst (bars “B”), and with the attached catalyst and a BPA purity of99.65 wt % (bar “C”).

FIG. 10 is a bar graph comparing the yellowness index (YI) for anexemplary polycarbonate (LEXAN* polycarbonate grade PC105 having a meltvolume rate of 6) with the bulk catalyst (bars “A”), the attachedcatalyst (bars “B”), and with the attached catalyst and a BPA purity of99.65 wt % (bars “C”).

FIG. 11 shows a comparison of the yellowness index (YI) for an exemplarypolycarbonate (LEXAN* polycarbonate grade PC135 having a melt volumerate of 4) with the attached catalyst (bars “B”), and with the attachedcatalyst and a BPA purity of 99.65 wt % (bars “C”).

FIG. 12 is a graphical illustration of change in YI over time forvarious grades of LEXAN* polycarbonate formed with the new catalyst orwith the new BPA using a free hydroxyl concentration of less than 150ppm.

Table 4 show the various formulations tested. Resin was compounded withvarious heat stabilizers at two different levels each. The dependency ofinitial color, color stability in heat aging and hydrolitic stability(molar mass stability in autoclaving) on additive concentration wasevaluated and rated quantitatively as ++(highly desirable),+(desirable), O (neutral), −(undesirable), −− (highly undesirable).

TABLE 4 HYDROLIC MVR Initial YI HA YI ** STABILITY CHANGE ¹ Irgafos168 + + + + ² Doverphos + + — + ³ PEPQ + 0 — + ⁴ Ultranox 626 + + — + ⁵TNPP + −− — + ⁶ TPP ++ 0 + + H₃PO₃ — −− −− + ⁷ DPDP + −− −− + ⁸ Ultranox1076* + + 0 + ⁹ Ultranox 1010* + — + + ¹⁰ HALS 770* — −− — + ¹¹ PAO* —−− + + ¹ Tris (2,4-di-ert-butylphenyl)phosphite ² Dioleyl hydrogenphosphite commercially available from Dover Chemical, Dover, Ohio ³4-[4-bis(2,4-ditert-burylphenoxy)phosphanylphenyl] ⁴bis(2,4-di-t-butyphenyl)pentraerythritol diphosphite commerciallyavailable from Chemtura Corporation, Middlebury, CT ⁵tris(nonylphenyl)phosphite ⁶ triphenyl phosphine ⁷ diphenyl isodecylphosphite ⁸ octadecyl3(3,5ditertbutyl4hydroxyphenyl)propionatecommercially available from Chemtura Coporation ⁹pentaerythritol-tetrakis(3(3,5-di-tert.butyl-4-hydroxy-phenyl-)propionate)commercially available from Chemtura Corporation ¹⁰bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate ¹¹ phenolic antioxidantN,N-hexane-1.6-diylbis[3-(3,5-di-tert-butyl-4hydroxyphenylepropionamide)] *tested on combination with 500 ppm Igrafos168 ** based upon 750 hours at 130° C.

As noted above, HPLC (high performance liquid chromatography or highpressure liquid chromatography) can be used to determine BPA purity. Setforth below are further details, according to embodiments.

Sample Preparation:

About 200 milligrams (mg) of the sample is weighed accurately. It isdissolved in 5 ml of tetrahydrofuran (THF) and 2 ml of a 10% solution ofpotassium hydroxide diluted in methanol. The depolymerization ofpolycarbonate is carried out with the use of these solvents.

The solution is shaken for 2 hours. Then, 2 milliliters (ml) of aceticacid are added to protonate the BPA carbonate salts and decrease the pH.The solution is shaken again for half an hour for homogenization anddissolution of all precipitates.

Standard Sample Preparation:

These samples containing only one impurity determine the retention timeand the calibration coefficient of each impurity. The impurity isdissolved in 10 ml of methanol. The mass is calculated in order toobtain a concentration in vial between 50 and 100 ppm. One ml of thissolution is taken and diluted in 10 ml of methanol.

All the different solutions are put in vials by the aid of a syringewith a filter. For both impurities and samples, a blank is made in orderto explain a strange peak or a problem in the solvent. The blank has thesame solvent composition as the sample. It means that for the standardsample the blank contains only methanol. For the samples, the blankcorresponds to a mix of 5 ml of THF, 2 ml of Methanol and 2 ml of AceticAcid.

Experiments:

The device used for the HPLC analysis is an Agilent 1100 system. Thesoftware used is Agilent ChemStation. The analysis is carried out on aC18 column. A gradient of polar solvents is used. It is a mixture ofwater and methanol. THF is used at the end of the analysis to clean thecolumn. Table 5 sets forth the solvent gradient profile.

TABLE 5 Time (min) H₂O + 0.1% H₃PO₃ (%) MeOH (%) THF (%) 7 60 40 0 31 1090 0 33 0 60 40 34 0 60 40 35 60 40 0 44 60 40 0

The applied flow is 1.2 milliliters per minute (ml/min). The output isrecorded as a series of peaks, each one representing a compound. Allpeaks are integrated on the chromatogram to obtain the peak area. Forall impurities except for DMX, the integration is done at 280 nm. Forthe DMX, the integration is performed at 254 nm because the peak is morevisible. To identify each peak, the retention time can be used but withcaution because in function of the conditions the retention time canchange (pressure, solvent, column, temperature . . . ). Table 6summarizes the different studied impurities (impurities contained in PCwith their corresponding retention times).

TABLE 6 Impurity Retention time (min) Phenol 2.44 IPP 7.49 ppBPA 10.69opBPA 14.66 1CD2 17.32 ²CD1 18.49 PCP 18.98 BPX 1 20.20 Chroman 1 20.66Chroman 1,5 22.49 SBI 23.38 BPX 2 24.11 DMX (254 nm) 24.58 1cyclicdimer-2, a1H-Inden-5-ol,2,3-dihydro-1-(4-hydroxyphenyl)-1,3,3-trimethyl- ²a cyclic dimer ofisopropenylphenol 1H-Inden-5-ol,2,3-dihydro-3-(4-hydroxyphenyl)-1,1,3-trimethyl-Determination of the Impurities Concentration in Polycarbonate:

The impurities concentration in polycarbonate is found from thechromatograms analysis. Then, the BPA purity can be deduced. Using thearea corresponding to the retention time for impurities, the impuritiesconcentration in the vial can be calculated. For that, the area of eachpeak is multiplied by 1,000 to obtain a concentration in milligrams perliter (mg/L) of each impurity in the vial. Then, it is divided by eachimpurity calibration coefficient.

${{concentration}\mspace{14mu}{of}\mspace{14mu}{{impurity}({vial})}} = \frac{{peak}\mspace{14mu}{area}*1000}{{calibration}\mspace{14mu}{coefficient}}$

From the accurate amount weighted at the beginning for each sample, theinitial concentration of the vial is calculated in mg/L.

The concentration of impurities in polycarbonate is determined bymultiplying the concentration of impurities in the vial by 1,000,000 inorder to convert the concentration in ppm. Then, this result is dividedby the concentration of the sample.

${{concentration}\mspace{14mu}{of}\mspace{14mu}{{impurity}({PC})}} = \frac{\mspace{50mu}{{{concentration}\mspace{14mu}{of}}\mspace{14mu}\;{{{impurity}({vial})}*1000000}}\;}{{sample}\mspace{14mu}{concentration}}$Determination of the Impurities Weight Percentage in PC:

The areas of unknown peaks that appear before the DMX peak are summed.The concentration of unknowns is determined by using the BPX-2coefficient. The use of this coefficient was chosen arbitrarily. All theconcentrations of known and unknown impurities (except BPA, phenol andPCP) are added. The concentration found in parts per million (ppm) istransformed to wt % by dividing by 10,000. Like that, the wt % ofimpurities is found in the resin.

${{wt}\mspace{14mu}\%\mspace{14mu}{of}\mspace{14mu}{impurities}} = \frac{\sum{{Concentration}\mspace{14mu}{of}\mspace{14mu}{impurities}}}{10000}$BPA Purity Determination:

After, a coefficient is applied to determine the wt % of impurities inBPA. The samples are weighted before depolymerization. The BPA molarmass is different from the carbonated BPA. For that, we multiply by 254grams per mole (g/mol) and divide by 228 g/mol. 254 g/mol corresponds tothe resin molar mass and the BPA molar mass is equal to 228 g/mol.

${{wt}\mspace{14mu}\%\mspace{14mu}{of}\mspace{14mu}{impurities}\mspace{14mu}{in}\mspace{14mu}{BPA}} = \frac{{wt}\mspace{14mu}\%\mspace{14mu}{of}\mspace{14mu}{impurities}*254}{228}$

The BPA purity is determined by subtracting the wt % of impurities ininitial BPA from 100. BPA purity=100−% wt of impurities in BPA.

In an embodiment, a composition comprises: bisphenol-A polycarbonate,wherein a molded article of the composition has transmission levelgreater than or equal to 90.0% at 2.5 mm thickness as measured by ASTMD1003-00 and a yellow index (YI) less than or equal to 1.5 as measuredby ASTM D1925. In an embodiment, an article comprises the composition.

An embodiment of a method of making a polycarbonate compositioncomprises: polymerizing by an interfacial polymerization, reactantscomprising a starting material comprising a bisphenol-A having a purityof greater than or equal to 99.65 wt % and a sulfur content of less thanor equal to 2 ppm, wherein the polycarbonate composition has a freehydroxyl content of less than or equal to 150 ppm, and wherein a moldedarticle of the polycarbonate composition has transmission level greaterthan or equal to 90.0% at 2.5 mm thickness as measured by ASTM D1003-00and a yellow index (YI) less than or equal to 1.5 as measured by ASTMD1925.

In the various embodiments, (i) the bisphenol-A polycarbonate cancomprise less than or equal to 150 ppm free hydroxyl groups; and/or (ii)the bisphenol-A polycarbonate comprises sulfur in an amount less than orequal to 2 ppm sulfur; and/or (iii) the molded article comprises anincrease in yellow index (YI) of less than 2 during 2,000 hours of heataging at 130° C.; and/or (iv) the bisphenol-A polycarbonate is aninterfacially polymerized polycarbonate; and/or (v) further comprising aflame retardant; and/or (vi) further comprising a second polycarbonatederived from bisphenol-A, wherein the second polycarbonate is differentthan the bisphenol-A polycarbonate; and/or (vii) further comprising asecond polycarbonate, wherein the second polycarbonate is selected fromat least one of the following: a homopolycarbonate derived from abisphenol; and/or (viii) a copolycarbonate derived from more than onbisphenol; and a copolymer derived from one or more bisphenols andcomprising one or more aliphatic ester units or aromatic ester units orsiloxane units; and/or (ix) further comprising one or more additivesselected from at least one of the following: UV stabilizing additives,thermal stabilizing additives, mold release agents, colorants, organicfillers, inorganic fillers, and gamma-stabilizing agents; and/or (x) thearticle is selected from at least one of the following: a light guide, alight guide panel, a lens, a cover (e.g., LED cover), a sheet, a bulb,and a film; and/or (xi) the article is a LED lens; and/or (xii) thearticle comprises at least one of the following: a portion of a roof, aportion of a greenhouse, and a portion of a veranda; and/or (xiii)further comprising dissolving a reactant in an aqueous caustic material,adding the resultant mixture to a solvent medium, and contacting thereactants with a carbonate precursor in presence of a catalyst; and/or(xiv) using an end-capping agent (e.g., endcapping the polycarbonate);and/or (xv) the end-capping agent can be selected from at least one ofthe following: phenol or a phenol containing one or more substitutionswith at least one of the following: aliphatic groups, olefinic groups,aromatic groups, halogens, ester groups, and ether groups; and/or (xvi)the end-capping agent can be selected from at least one of thefollowing: phenol, p-t-butylphenol, and p-cumylphenol; and/or (xvii) themethod can exclude use of a melt polymerization process to make thepolycarbonate. Also included herein are articles formed by any of theabove methods.

It is noted herein that all weight percents do not exceed 100 wt %.

Also, all ranges disclosed herein are inclusive of the endpoints, andthe endpoints are independently combinable with each other, andinclusive of all intermediate values of the ranges. Thus, rangesarticulated within this disclosure, e.g. numerics/values, shall includedisclosure for possession purposes and claim purposes of the individualpoints within the range, sub-ranges, and combinations thereof.

Reference throughout the specification to “one embodiment”, “anotherembodiment”, “an embodiment”, and so forth means that a particularelement (e.g., feature, structure, and/or characteristic) described inconnection with the embodiment is included in at least one embodimentdescribed herein, and may or may not be present in other embodiments. Inaddition, it is to be understood that the described elements may becombined in any suitable manner in the various embodiments. Variouscombinations of elements of this disclosure are encompassed by theembodiments disclosed herein, e.g. combinations of elements fromdependent claims that depend upon the same independent claim.

The suffix “(s)” as used herein is intended to include both the singularand the plural of the term that it modifies, thereby including one ormore of that term (e.g., the colorant(s) includes one or morecolorants).

In general, the compositions or methods may alternatively comprise,consist of, or consist essentially of, any appropriate components orsteps herein disclosed. The invention may additionally, oralternatively, be formulated so as to be devoid, or substantially free,of any components, materials, ingredients, adjuvants, or species, orsteps used in the prior art compositions or that are otherwise notnecessary to the achievement of the function and/or objectives of thepresent claims.

As used herein, “combination” is inclusive of blends, mixtures, alloys,reaction products, and the like.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

While particular embodiments have been described, alternatives,modifications, variations, improvements, and substantial equivalentsthat are or may be presently unforeseen may arise to applicants orothers skilled in the art. Accordingly, the appended claims as filed andas they may be amended are intended to embrace all such alternatives,modifications, variations, improvements, and substantial equivalents.

What is claimed is:
 1. A method of making a polycarbonate compositioncomprising: polymerizing by an interfacial polymerization, reactantscomprising a starting material comprising a bisphenol-A to form abisphenol-A polycarbonate, wherein the bisphenol-A has a purity ofgreater than or equal to 99.65 wt % and a sulfur content of less than orequal to 2 ppm; wherein the polycarbonate composition has a freehydroxyl content of less than or equal to 150 ppm, and wherein a moldedarticle of the polycarbonate composition has transmission level greaterthan or equal to 90.0% at 2.5 mm thickness as measured by ASTM D1003-00and a yellow index (YI) less than or equal to 1.5 as measured by ASTMD1925, and wherein the molded article comprises an increase in yellowindex (YI) of less than 2 during 2,000 hours of heat aging at 130° C. 2.The method as in claim 1, comprising dissolving a reactant in an aqueouscaustic material, adding the resultant mixture to a solvent medium, andcontacting the reactants with a carbonate precursor in presence of acatalyst.
 3. The method as in claim 1, further comprising adding anend-capping agent.
 4. The method as in claim 3, wherein the end-cappingagent comprises at least one of the following: phenol or a phenolcontaining one or more substitutions with at least one of the following:aliphatic groups, olefinic groups, aromatic groups, halogens, estergroups, and ether groups.
 5. The method as in claim 4, wherein theend-capping agent comprises at least one of the following: phenol,p-t-butylphenol, and p-cumylphenol.
 6. The method as in claim 1, whereinthe method excludes use of a melt polymerization process to make thepolycarbonate.
 7. The method of claim 1, wherein the bisphenol-Apolycarbonate is a homopolycarbonate derived from bisphenol-A.
 8. Themethod of claim 7, wherein the bisphenol-A polycarbonate is a linearhomopolycarbonate derived from bisphenol-A.
 9. The method of claim 1,further comprising adding a second polycarbonate derived frombisphenol-A polycarbonate, wherein the second polycarbonate is differentthan the bisphenol-A polycarbonate.